Eh, it depends. If you've only ever had customer service interactions with them don't. But if you've actually have a human dynamic it's very different.

I have no end of creeps hitting on me at work. But there was this one customer who I would just chat with every time they came in. Nothing really flirty, but it was a really welcome distraction from work. Eventually they asked for my number, and it wasn't weird at all. We even have a date planned tonight.