Thanks all, your stories made me feel better. But what I really want to know is the next time I see her (and I know I will) is should I greet her the same way I always have? I'd like to. Because even though we're only acquaintences (meaning we've never met outside of that store), she is a very pleasant person and I Do like talking to her in that scenario. Or would you think that would make her uncomfortable. And if I do, and she seems uncomfortable, what should I do then?
I'd say, start the same way you always have.
Because she is NOW an acquaintance of yours, right? She's that nice lady you see in that store. So approach her that way.
If she seems uncomfortable, then dial down rapidly and find somewhere to go right away (but naturally).
I think you can even ask about her mom, in a sort of "your mom's well-being affects you--I hope that's going well" way.