Daniel Saidenberg ws the first cellist of the Philadelphia Orchestra, conducted by Leopold Stokowski.  He recalled:

Stoki’s ability to exert disciplines was occasionally matched by a sense of humor.  After a concert at which I had played the Saint-Saëns A-minor Concerto, one of my buddies said, “Watch your step, Danny.  All through the second movement, Stoki was looking at you with fire in his eyes.”  I hadn’t noticed anything, but sure enough, the manager came over, saying that Maestro wanted to see me.  Now came the confrontation.  “Saidenburg, why didn’t you look at me during the concerto?” Stoki asked.  “Where were your eyes?” I was nonplussed but decided it would be better to tell the truth than some story.  “Well, Maestro,” I said, I was looking at my new girlfriend, who was sitting in the second row.”  With that Stoki patted me on the rear, and said, “I can well understand that, but don’t let it happen again.”

Chasins, Abram (1979) Leopold Stokowski: A Profile.  London: Robert Hale, p.108.