I wouldn't necessarily read too much into this, pd. It could well be as nannywoofwoof and Yoda suggested. I've been the person they suggested. I'm a shy and (generally ) a pretty nice person, but would usually only make a little wave or something if I saw someone across a store. Actual talking would be rare. It has absolutely nothing to do with them, I just suck at chitchat.(And growing up being told that talking to people = bothering them probably didn't help.) Sometimes it's everything I could do just to get out to the store and am already psychologically maxed out. Even a short conversation would be too much. Going forward would make it inevitable to deal with. Only other option is to go the other way. I would especially panic if they didn't know of my problems. A) It's pretty obvious at such a time that I have them and B) it's sure as hell not the way I'd want the subject to come up(!)

Also, I'd be especially mortified if it were someone I knew from way back and had only recently reunited with. Might not be first impressions, but it's still best-face-forward time.

Now, if the situation had been her walking by you and pointedly sticking her nose up in the air, that'd be a pretty clear cut snub. This one? Not so much. Too many potential reasons why it could have happened that would have nothing to do with you.

(And you say she's gone uber-religious -- maybe there's trouble in paradise, doesn't want to admit it and is afraid she can't hide it.)