@cadaverock,
Why aren't you going with her?
Seriously, dude, you can see for yourself that it's likely nothing sketchy. Stewing at home is doing you no good.
Oh, and BTW, if you say you're going and she tells you not to (with any reason other than
you won't know anyone there), then you're right to smell a rat. But right now, you have no idea.
So, why not observe her and her coworkers in the wild, as it were?
You just might, oh, I don't know, have a good time and make friends.