well, I don't know about grocery shopping, but a few years ago I was freaked out in the Bed Bath & Beyond here in Manhattan when suddenly the clerks were saying "Hi!" to me as I walked past them. I kept thinking, "Do I *know* her? That was an awfully familiarity-sounding greeting!"As if she was so extra-pleased to see me.
They also would walk up and say, "are you finding everything?" and "Let me get you a cart," which was nice, but when they first put their "extra friendly" strategy in place, it creeped me out.