Sorry for the long post but I need opinions please

(Also yes I know I should have left when I found out but that's the past so now I need to know if he's cheating again)

Long story short I found out my boyfriend cheated August 2018. It wasn't sexual because she lived in another state but it was a relationship.

I haven't found anything since then that pointed to cheating until a few weeks ago and now I need to know if he's cheating again.

Basically I walked into target with him and this girl at the counter yells from like 20+ feet away "Hi Michael!" Really excited and she's waving and everything but he didn't even look her direction and she recognized him...

I ask him who she is and he shrugs it off and says he doesn't know her (obviously she knows who he is though) but he does come here often for work because it's convenient.

We have mostly the same friends and I've never seen her before so it's probably not just one of his platonic friends. (Idk maybe it is)

Either way, I keep asking wtf was that whole we are in the store and he tells me that he think her name is Alyssa (my name too) and that he has checked out with her before.

Every time I ask him how she knew his name he said that she probably got it off of his card but at target you insert your own card so idk why that's a possibility? (He doesn't wear a name tag for work so that not it either)

He swears he's not cheating but I seriously cant get over it or figure out how she would know his name and be so excited to see him..

Do you think he's cheating or flirting with her?

Thank you for the help. Also, sorry about the bad grammar... I get shaky when I think about it and it makes it hard to type