It appeared to be no big deal the other day when the 28 National Football League club owners voted to keep their traditional draft of college players in April instead of advancing it to February. Seemingly a trifling decision. Hardly newsworthy. What difference would a couple of months make?

Plenty. This was the NFL taking all due care at this important point to maintain a most serene innocence in all matters. It was necessary. The league had just been slugged with a thumping $1.32 billion antitrust suit by the young U.S. Football League, which is charging monopoly, conspiracy and dirty tricks by the NFL to control pro football and limit competition.

To move in now on the February draft date that for two years has been a USFL exclusive could have been damning for the NFL. At something like this, the courts might utter a harrumph. Better to let the new league have its jump on trying to sign the pick of the collegians than for the NFL to do anything that might be evidential.

Whether the USFL suit is frivolous and foredoomed and, as Pete Rozelle claims, "the last gasp of a dying league," the NFL is properly sensitive to antitrust actions.

It recently lost one, to the sour tune of the $50 million damages it has been ordered to pay Al Davis for obstructing his move of the Raiders from Oakland to Los Angeles. The NFL is waiting on an appeal to the Supreme Court but, meanwhile, the interest that may be awarded to Davis has been piling up.

In previous years, the NFL did win antitrust actions brought by the old American and World football leagues, but 2-1 in the won-lost column is no longer reassuring. And there is nothing ragtag about the legal attack the USFL is mounting.

The financial resources are there. They are provided, among others, by Donald Trump, who owns the New Jersey Generals and who has taken a major leadership role in the league.

Trump builds 57-story skyscrapers in New York out of petty cash, and owns the newest Atlantic City casino. The man he tapped as counsel for the USFL in this thing is Roy Cohn. He's Trump's personal lawyer who recently won a $72 million real estate tax abatement for Trump in New York City.

Already, they are playing hardball. Cohn is saying he has evidence that the NFL has devised a "secret committee created exclusively for destroying the USFL." He is making it sound very stealthy -- "We have reason to believe we know who they are and what they are doing."

This has caused the NFL and others to laugh quite loudly. "We have a long-range planning committee and everybody knows who they are," says an NFL spokesman. "We announced it openly last March in Hawaii -- a six-man group headed by Wellington Mara and Lamar Hunt. It's about as secret as the daily sunrise, and the USFL has the same kind of planning committee." So there.

Trump, who persuaded the USFL to switch from a spring to a fall schedule in 1986, is very upbeat about his league's action. "The NFL is petrified by the suit," he told The New York Times.

Certain NFL owners admit they are "concerned," not by the merit of the suit but because, as one of the owners said, "You never know what a judge will do."

Among certain people the wisdom is that Trump and others are simply trying to batter their way into NFL franchises, hopeful that by bringing a huge suit they can force a buy-off with expansion franchises or a merger, as some old AFL teams did.

Rozelle is offering Trump no encouragement. Before the suit he said, "We have no plans for taking any teams in," and obviously he does not find Trump any more endearing now. Rozelle has called the suit "baseless" and seems to show he is streetwise by declaring, "Antitrust action has been the game plan of every 'second league.' "

The NFL people say that while the USFL is including the major networks in the alleged conspiracy, significantly, it isn't including the networks in the suit. That's because the young league still has hopes of doing business with them, business that is necessary to keep the league alive. Only ABC, on a modest pay scale, has shown interest in USFL telecasts. Cohn has said the networks might be targets later -- in effect telling them to shape up or else.

That the NFL is responsible for the failures of the USFL may be questionable. It wasn't a very bright idea in the first place to try to play pro football in the spring and summer, barely two months after the NFL season had saturated football interest and when the fancy of the fans would turn to other persuasive interests like baseball, the Masters golf, the Triple Crown races, college and pro basketball playoffs and all-star games. It was forbidding competition.

The USFL has been a two-year financial disaster with admitted losses of $100 million. Seventeen of the 18 teams were money losers last season, with only Denver showing a profit.

And not all of the clubs were enthusiastic about Trump's idea to move to a fall schedule and go head to head with the NFL. One disenchanted owner told a Baltimore newspaper, "It was a foolish move to vote a lame duck spring season in 1985 and then play in the fall of 1986. But what do you expect when 18 fools get together?"