It's hardly that unusual in my experience - and of course not only among Muslims (as you may know there's a quite sizeable and visible Chasidic community in Antwerp, where I live).

Of course, you can't always tell how they'll react before you try it, in the case of Muslim women, so it's inevitably awkward, you don't want to make assumptions beforehand and not offer your hand at all either (except perhaps if the woman in question is wearing a burqa or other indication that she's likely to be archconservative).

I guess it depends on how used you are to touching people during conversation... personally I'm not at all, so I don't really see how the not shaking one's hand thing, specifically, would be such an issue. Of course there will be other cultural differences that are linked to that, and some of those might lead to awkward situations - but there's not really very much that you can deduce from that one point alone (or not much that her hijab hadn't already told you, anyway). She could still have quite liberal ideas about things.

Heh. Might wanna watch out there, alright.