Can You Help?

This question was recently submitted to the Robert Benchley Society. Can anyone help answer it?

"Many years ago I read a wonderful story by Benchley in which he talks about all the clever things he wished he had said to someone at the time, but only thought of later, after his opportunity to say them had passed. Even though I have looked through all of the titles we have here by Benchley, I haven't been able to find that story. Every once in awhile I try again, to no avail.

"Best regards,
M.H."