For a month, there’s been a constant buzz in Washington surrounding the Redskins’ exhibition season. Was it an omen, a tease, or just a grand illusion?

For now, after a 28-14 season-opening victory over the New York Giants at FedEx Field, it appears to be this: a logical progression.

Logical, at least, if you’re Coach Mike Shanahan or one of the Redskins who, in the words of quarterback Rex Grossman, “trust him with everything. We love playing for him, respect him and we believe.”

The Kool-Aid’s being passed. Care for a mug? Tastes good so far.

The positive, but inconclusive signs of improvement that showed up sporadically last year now appear to have been Shanahan’s seeds of future growth. Then, the Redskins, even in their numerous close defeats, showed that their days of utter madness — constant intrigue, mental errors and slack habits — were quickly coming to an end.

By the kind of symmetry you seldom see, the Redskins ended last season against these same familiar Giants, the franchise in the NFC East that has come closest to owning them in recent years. That day, also in FedEx Field, the Redskins finished their 6-10 season by losing 17-14. Some saw nothing more than continuing frustration. The margin of defeat was a botched 30-yard field goal. Pure contemporary Redskins? Shanahan disagreed.

“We had six wins and there were six or seven other games like this one where, with different scenarios, it could have been different,” Shanahan said. “Next year, hopefully, we will learn how to finish.”

Now, the signs of order and cohesion are starting to become clear. The Giants arrived here badly injured, especially on defense, and distracted, to a degree, by a Plaxico Burress-pops-off controversy. But they also arrived as favorites.

“If you are going to [finish], you’ve got to make plays at the right time,” said Shanahan whose team, in the bad old days of ’10, might have been rattled after a Grossman sack-and-fumble gave the Giants the ball at the Redskins 27-yard line in the fourth quarter, with the Skins ahead, 21-14.

“We had a chance [to put the game away] in the third quarter, but we didn’t do it,” Shanahan said. “When you [let opponents] hang around like that, sometimes you get bitten.”

This time, the Redskins did the biting. Linebacker London Fletcher stuffed an Ahmad Bradshaw run for a two-yard loss on third and one from the Redskins 18. When the Giants tried a 38-yard field goal, the Redskins blocked it, with a picture-perfect special teams play worthy of the George Allen era as defensive stalwart Brian Orakpo got his hand on the ball. Surely general manager Bruce Allen smiled and remembered.

Grossman, otherwise excellent all day, was eager to atone. “Obviously my fault,” he said of the fumble. “Just a bad play.” The Redskins ripped off a 70-yard drive that culminated in his second touchdown pass of the game — a four-yard dart to Jabar Gaffney for a 28-14 margin.

Giants: Finished.

Don’t make too much of one game against a gimpy foe. Osi Umenyiora, Justin Tuck, Jonathan Goff, among others, weren’t there. But don’t make too little either. The Redskins needed an infusion of new talent. Early in the second half, their No. 1 draft pick, linebacker Ryan Kerrigan, batted an Eli Manning pass in the air, intercepted it and ran nine yards for a touchdown to break a 14-14 tie.

Giants Coach Tom Coughlin was of the opinion that the play rather spoiled what had been, until then, “a very, very good and competitive football game.” After that, it was a very — oh, what is that word — “Redskins” kind of game.

“At halftime, we said we wanted to have more swagger, fly around more, have a little more fun [on defense],” said Kerrigan, who described the game-turning play simply. “Play the cut block, get my hands up. Fortunately, the ball found my hands — twice.”

The pure silliness of changing position, from defensive end in college to linebacker, and then blowing up the first NFL game he ever played in, wasn’t lost on Kerrigan.

“I never scored a touchdown in college. The last time on defense was in high school,” said Kerrigan, grinning.

“I’ll always remember not being able to see anything at all when I was being mauled by my teammates in the end zone.”

It wasn’t just the top of the draft who produced for the Redskins. The next-to-last player picked — the fellow who was almost Mr. Irrelevant — nose tackle Chris Neild from West Virginia had two of the Redskins’ four sacks.

“Two sacks, by a nose tackle? No, you don’t see that much,” said Shanahan, trying to keep a straight face. Odds on such a Neild day, maybe a million-to-one.

The Redskins also needed to find high-talent low-ego free agents who would fit into their system-first worldview. Running back Tim Hightower, a graduate of Episcopal High, played every meaningful down, rushed for 72 yards, caught passes for 25 and ran for a touchdown.

Exactly a decade after the attacks on Sept. 11, 2001, the Giants were the proper opponent for a display of national solidarity with teams from the two major cities that were attacked. Passions ran deep among players on both teams. But the Giants were also the ideal foe to show how well the Redskins had learned their lessons since the last meeting.

“I was overwhelmed,” said Grossman of all the pregame patriotic celebrations. “It was a fun day I’ll never forget.”

Now the Redskins will confront what is perhaps the defining predicament of the franchise for the last decade: expectations. Suddenly, they may have them on their shoulders once again. How many times has that insured a flat performance the next week, especially at home?

The pundits predicted that they would win only three or four games with the likes of Grossman at quarterback, but they have already beaten the Giants, who were 10-6 last year. Can 5 million people take a cold shower simultaneously and vow not to mention the word “playoffs?”

“We still have a lot to work on,” said tight end Fred Davis who caught five passes for 105 yards.

Yes, but not nearly as much as many thought.