The story surfaced today in The New York Times from one of Kennedy's Oval Office recordings just released by the Kennedy Library.
Dupuy explains it himself at the KSFR site:
The President was yelling at an air force general about preparations being made at my base just in case a pregnant Jackie Kennedy went into labor on one of their frequent weekend visits to their Cape Cod summer home. The place was a base on Cape Cod where yours truly was serving as an Air Force second lieutenant in charge of media relations. Air Force One regularly landed at my base during the summer so the Kennedys could spend a weekend at Hyannis Port. My job was to handle local media and the White House press corps on these visits.
The air force had secretly cleaned up a wing in a World War II era hospital for Jackie Kennedy just in case. Word got out. The press showed up and air force headquarters in Washington told me to escort photographers and reporters to the hospital wing. I did. I showed them the spartan room, the bed and the rocking chair placed by the bed for JFK's personal use. The reporters insisted I get into the picture to provide a human touch. I did. It was that photo that JFK saw the next day in the Washington Post.
The president was angry because he was afraid taxpayers would think the $5,000 spent on the hospital room was a waste of money.
The KSFR site has the actual recording of JFK railing about the "silly bastard" who was endangering the Air Force budget.
I'm jealous. I've been called a lot of names by a lot of politicians, but never a president. Congratulations, Bill.