Well, first off, I would like to say that I hate it when a female does that. I don't know why they do it, but it seems to be universal or something
... It's just another of life little mysteries concering women.
Anyway, my advice would be to just leave her for now. By the fact that you have called multiple times and she hasn't bothered getting back in touch with you, it's a bit evident that she doesn't want to talk to you at the moment. As you stated, I wouldn't be so quick to jump to a conclusions (Even though it sounds as if she might be rethinking the relationship).