I mean, this sounds like something one would do on accident. Well, it more certainly sounds like something I would do. I can't tell you how many times I've absent-mindedly put something in the refrigerator that didn't necessarily belong there.
The employee clarified that yes, the bags were for her purchases that she'd JUST made at the store. When she asked what alternative did she have to take her purchases out of the store, he told her she could either put them in her purse or carry them out.