One slim possibility that I can think of would be the filter. I can't imagine the height they would have had to drop the trans from in order to dent the pan deeply enough to damage the filter, but filter damage could cause a whine. If the pan did bend the filter enough to crack the neck or damage the seal, or if they had the filter off for some reason and damaged the seal, the pump could suck air around the seal and cause a whine due to cavitation. It's a slim possibliity, but a possibity nonetheless.

Something to look for while the pan is off next time, anyway...