It's possible that mice got into one stash of the food she doesn't like (the rest of it is in a glass jar and the good stuff is in a metal cannister). But she doesn't seem scared of mice -- she's quite good at catching them, and shows intense interest anywhere there's sight, sound, or scent of mose activity.
She's just not good at killing them. She gets overconfident while playing with them.
Re:
She's just not good at killing them. She gets overconfident while playing with them.