The Fredösphere

I was just telling my friend John a story I read a loooooong ago about Benny Goodman rehearsing Igor Stravinsky's jazz-influenced Ebony Concerto.  At one point Stravinsky was struggling at length to describe the expression he wanted on a particular note.  Finally, the light came on for Goodman, who turned around to his band and said, "bend it, boys!"

Did that really happen?  This anecdote is resisting my attempts to google it.  It's been so long since I read it, my confidence in the accuracy of any particular detail is about nil.  If you can confirm, deny, or correct my memory, please comment.