For Moose and others: Change the call?

[DJWickham]

Slightly off subject, because Moose is arguing about "may" rather than "should" for changed calls, is this reference I found to Bill Klem:

"He could be stubborn. He reportedly once started to call a runner out at the plate, then signaled safe when a ball rolled loose. The catcher showed him he still held the ball; the loose ball had apparently fallen from one of Klem's pockets. He refused to change his call."

from Bill Klem, The Baseball Online Library.