A LOUD MOAN of disbelief greeted White House spokesman Marlin Fitzwater the other day when he bounded into the press room to announce that Ronald Reagan will travel to South Bend, Indiana, to dedicate a postage stamp.

Not even Fitzwater's one-liner -- "The gipper goes back!" -- managed to silence the grousing in the press corps.

But, then, few presidents have been able to resist the standing offer from the Postal Service to attend stamp dedication ceremonies, and for Reagan the chance to invoke the memory of the role that actor Pat O'Brien said "made Reagan a star overnight" may have been too much.

The stamp the president will help celebrate is a 22-cent commemorative honoring the 100th anniversary of the birth of Notre Dame University's famed football coach, Knute Rockne.

In the 1940 movie "Knute Rockne, All-American," Reagan portrayed one of Rockne's charges, George Gipp, a member of the football squad who died in his senior year. During a locker room scene at the halftime of a game with Army, O'Brien, playing Rockne, offered the movie's most memorable line: "Win one for the Gipper."

The phrase stuck with Reagan, who until then had been a sports announcer turned mediocre actor. One of the stories that Reagan has told for years is how he won the role by showing off pictures of himself in his Eureka College football uniform.

It's a tale stamp collectors and others will probably get to hear again when he mounts the stage at Notre Dame for the first-day ceremonies on March 9. His prop this time will be the vertically designed commemorative bearing a portrait of the balding Rockne holding a football.

The stamp was produced by the designer Peter Cocci and engraver Thomas Hipschen at the Bureau of Engraving and Printing's new electronic design center in Washington. According to the Postal Service, Cocci prepared "a concept sketch" based on a photo of the coach.

Hipschen then engraved the portrait which was scanned electronically so Cocci could use computers to add lettering and decide on coloring.

Not surprisingly, the colors he chose for the lettering of Rockne's name are blue and gold, the colors of the Fighting Irish.

The stamp is the sixth in the American Sports Series and the second to honor a football player. Jim Thorpe was pictured on a 1984 stamp in the series. The new stamp will be issued before the expected increase in first-class postage to 25 cents and is the last 22-cent commemorative the Postal Service is planning to issue.

Some collectors may suspect this is not the first time that Rockne has been on a U.S. postage stamp. He bears a striking resemblance to the coach on a 1969 stamp honoring collegiate football, but Postal Service officials say that the figure is not Rockne.

It is the second time that Reagan has participated in a first-day ceremony. He went to the Pentagon in 1984 for a commemorative celebrating the contributions of Hispanic Americans, a stamp the White House ordered up. Last year Reagan unveiled a design for a stamp, expected to be issued later this year, honoring Dr. Harvey Cushing, a famed neurosurgeon.

That's hardly enough to mark Reagan as the No. 1 philatelist at 1600 Pennsylvania Avenue. That honor, of course, belongs to Franklin D. Roosevelt, a lifelong stamp collector who personally approved every stamp issued while he was president.

Individuals have until April 8 to have their requests for first-day cancellations of Rockne stamps postmarked. The stamps go on sale nationally on March 10, and collectors who buy their stamps locally should mail their first-day envelopes to: Customer-Affixed Envelopes, Knute Rockne Stamp, Postmaster, Notre Dame, IN 46556-9991.

The Postal Service will affix stamps on up to 50 covers at 22 cents per stamp at: Knute Rockne Stamp, Postmaster, Notre Dame, IN 46556-9992.

Bill McAllister is a member of The Washington Post national staff.