Generally speaking, chicks don't initiate calls with guys. They're usually on the recieving end.
It could be any of those things, but don't think that this is a situation that's completely unique to you. Don't worry about it. It happens to all of us. If she doesn't call back, call back at another time. Repeated unreturned calls, however, is a pretty loud and clear "**** off."
I don't even leave messages anymore unless some urgent situation is in question. And actually, I find that if a girl is going to call you back, she'll call you back quicker if you DON'T leave a message (assuming it's a bull**** smalltalk message). Guess it rouses curiosity or something.
Anyway, I'm going off-topic. Yeah, it could be any one of those things you listed. No, without knowing your specific situation (how the date went, you all's personalities, etc.) I can't take an educated guess at which one it is.
In the end, I wouldn't worry about it. Making an assumption like that off of one unreturned call is pretty rash, in my opinion.