I can't speak for all species of frogs, but I group feed my Fire belly toads, and occassionally a limb will be mistaken for grub in the feeding frenzy. Though I watch all feeding sessions, I have yet to have to intervene and none of my toads have gotten hurt. I don't know if maybe they taste bad to each other because usually the foot or front limb gets spit out rather quickly. Grey tree frogs might be different, so it is probably a good thing you helped Waldo release his unintended snack.