That does sound frustrating. I hope that she gets back to you... it sounds like she's been good at responding in the past?

If she doesn't... I'd totally write again and check it out with her. Like others said, ask if she got the message and let her know that you didn't hear anything back. She may have gotten interrupted, had an emergency, or just had a lousy day and forgotten. Or, she may have written back and it could have gotten lost in cyberspace (yes, I know that it sounds crazy! But it happens, I've had someone send me 2 emails in a row... and only the 2nd came through! I would never have known, except he referenced the first, and I was confused and emailed him back).

There's nothing wrong with writing back to ask if the message made it through! It's a good way to find out what actually happened. I find that, if someone has been consistent and respectful with me since I've known them, then when something like this happens, there's usually a good reason (i.e. it's not that they suddenly don't want to talk to you anymore).

Hang in there... I hope you hear from her soon!