Sure you realized you were beat as soon as she gave that little smile, but I doubt there was any ambiguity about whether you were paying attention or didn't understand the betting in that situation. Which is exactly my point. I believe that it is usually (sure not 100%, somebody MIGHT get away with something, once) easy to tell when it is a mistake vs. an angle shoot.
As Stuart pointed out, holding someone to a call just because it's VERBAL rather than physically putting chips in (which I think you agree has an exception for gross misunderstanding?) is just not in the spirit of the game. Especially in a tournament I think.