The original version of this story was three or four pages longer and ended with Sammy going to the beach to look for the girls and not finding them. Updike's editor at The New Yorker made the cut. The author was ultimately happy with the decision and turned the extra pages into a story called "Lifeguard," also found in the collection Pigeon Feathers (source).
John Updike's mother worked as a salesperson and had a boss named Lengel, the name of the party-pooper manager in "A&P" (source).
John Updike was also a visual artist and even went to art school for a year (source).