agree with trippin here first. But I wanted to add a couple things here.

First, she was flirty with him and apparently he was ignoring her, and noticeably so since you made a point of saying this. This is a good sign on his end. Her being an "awesome person" doesn't necessarily mean anything. I can say that about my best friend that I have in SC and he's just another guy I've talked to for years.

The "our store" thing, would bother me also but there was a reasonable explanation. He probably never thought anything of it.

Now as for the lady friend, I am not so sure about and I dont' want to raise any unnecessary flags for you but she seems to be the only one flirting here. Many people, guys and gals, can deflect such thing easily and not act on them. To his credit there doesn't seem to be any instigation here on his part by way of flirting back.

I would say like Trippin says don't ruin a good thing. He may be on the up and up and you may just be feeling insecure, albeit understandably so.