I don't see anything wrong with asking that question. I think you're pretty brave to do it directly like that; I don't know that I ever have. You might tell her it's important because you want to know whether she's into her job. I had one T tell me pretty bluntly that he wasn't all that into his job.

It's just seems like she's imposing a certain distance between the two of you by not answering the question. Perhaps there's some school of thought behind this that I'm not aware of.