I think you just had the unusual bad encounter, and on your first trip, it's not a confidence builder.
I've carried all around Virginia, and in western NC a lot, with never a reaction like that.
You could have simply stated "I'm ready to pay for this now." and let it go, but I certainly understand how you were discomfited by her reaction. Hope that it doesn't turn you off OC completely -- apparently your trip to Kroger was uneventful.
Sorry your first trip had to turn out this way.