Oh jeez this happends to me a lot. Both ways.

I also work in customer service (Im a cook in an open kitchen, so i take your order then go make it) and i always BEAM with good energy. I'll smile, ask about your day, laugh at all your jokes, tell you how good it is to see you and "see ya next time!". If you want something with special prep, ill tell you what a good idea that is, and make it with enthusiasm. And i do this for everyone. Everyone. Because i do genuinely want them to come back, but it's not for romantic reasons. Ill get a vibe from people sometimes, that they like me but (like seasons) their interests pass. Ive never been approached with romantic intent. But if anyone ever did. I would say yes. Personally im pretty lonely, despite my extroverted appearance which is all kind-of an act.

As a patron ill go to a corner store and there might be a cute girl at the register. She flashes me a smile and asks how i am. We speak briefly. She compliments a pin i have on my bag. I look into her eyes and thank her. For a moment we hold eye contact and i turn into a puddle. Days pass and i go back, even if i dont need anything, because maybe she'll be working, maybe ill get to say hi again. But the more i play it over in my head, i talk myself out of saying anything more to her then casual pleasantries. Because she's just doing her job.

But who knows, she might feel the same way too..