As I keep thinking about this I'm about 85% sure that it was a cashier specific policy but whether it was store mandated for her or not I don't know. I vaguely remember her saying something like "when you come through my line you do..."
She also mentioned that it has happened before which makes me think a situation occured that directly affected her. Or maybe it happened to her kid.
Maybe her motherly instinct is trying to "protect" all the kids.
Two courses of action I may take...
-Call the store manager up and tell them I felt disrespected and ask if it is standard practice. If so I will say I will take my business elsewhere and then probably continue to shop their anyway.
-Just be lazy and try to forget about it