(yet another one of these..) does she like me?

right here's how it goes. I've only know this girl for about 10 weeks (we're on the same corridor in school halls of residence) and we've gotten along very well the whole time. A few weeks ago during a film, she let me hold her hand, and since then has seemed perfectly comfortable with me popping around to her room to say hello, and having my arm around her waist/ holding her hand if we're watching something on the internet for example (this is if we're alone, not with others around, and so far things have gone no further than a long, close hug when I leave to go back to my room). Anyway, about 3 days ago, I feel like something has changed. She seems to be talking differently to me than she is to others on the floor- as in sometimes she seems a tad nervous around me? Seeing as I've had a lot on over these last few days I haven't had the chance to ask her, but I sent her an email asking if there was anything I'd done wrong and she didn't reply. I may be worrying too much, but I really do like her and hope to take things further in the future so i don't really want to find I've been 'barking up the wrong tree' as it were. What do you think? Playing hard to get or just suddenly not interested?