Girls, If she doesn't know me why would she wave and smile when we lock eyes?

She kinda knows me. But she only does this with me and no other customer. I've gone to lots of coffee shops as a regular customer. But never been treated like this by a coffee shop waitress. This girl seems more special as she ls the only girl who giggles when we talk, taken note of where I work and smiled and waved to me when her co-worker was serving us.
Girls, If she doesn't know me why would she wave and smile when we lock eyes?
Post Opinion