Stealing

I saw that there were some grapes in the store today "sans pepins." I tried one (not allowed) -- not great, but I feel that I have to support seedless grapes in France, so I bought some. I tried some other grapes, also 5€/kilo, which were delicious. I shoved them all in the same plastic bag, and went to the register. The woman looked at the grapes and started to take one bunch out. I told her they were the same price, but she said she needed to ring them up separately. Then she informed me that the good grapes were 20€/kilo. I'm pretty sure she thought I was trying to steal them, as opposed to just being a dumb-ass who doesn't read the right sign.