pinktweet, no, hv not asked her b4 why she did, except for the time when she 'pinch' the dessert which she was cutting, i confronted her... apart from that i did not...
well, i don't think she is the thrifty kind because just over the weekend, she threw away perfectly good cooked rice! all because she can't finish it (we usually leave her her portion of the rice in the rice cooker and she usually finish up everything (at least until last sat i tot so!)... when i saw the rice in the dustbin, i asked her why, she told me that the rice dropped on the table! even for us, when rice drop on the table, we will pick it up to eat also since table was cleaned b4 eating what... anyway, my mum noticed also that she is quite selective towards food (although she may not say so), cos can tell from her facial expression if the food is something she likes, her eyes will light up, otherwise, she appear a bit disappointed!
for 'pinching' food, i think it's a bad habit, cannot be she's hungry, very difficult to stop bad habit...
sigh, the problems with all these is that i can very rarely catch her red-handed as she always divert to do other things (very quickly) once she knows we come out of the room or into the place where she is in... but can always tell when we discover the 'evidence' later on...