Is it creepy?

I work as a barista. This cute guy came in and I looked at his name on his credit card when he paid. He was really cute and flirty but we didn't have much time to talk. He came in again with a female friend and they both made it very clear they weren't together. Unfortunately we were busy so I had to shuffle them down the line.Is it creepy to message him on ig/Facebook since we didn't have a formal name exchange? Is it creepier for a straight person to do this? My hope is that it's flattering.