So what should i think?

Okay, so there's this guy from my school and i had two classes with him. About 3 weeks ago he started talking to me a lot out of no where. He always seems to be the one to start up the conversation. Always ask me questions about the class and what we ended up doing if he was gone the day before. Then in our second class, he would always sit by me. Of course there is always space between desks, but he would scoot his desk as close as can be to mine (it would literally go under my desk). His arm or elbow would always be touching my arm in some way or form. He would always be playing something on his pod, and when he would win he would show me. I think he liked showing me because my chin would literally be on his shoulder when he would show me. Then we started texting, i got his number. And i think he seemed kind of happy at first, but then he his text message responses would start getting shorter and shorter. In person it seems like he enjoys talking to me, because his eyes seem to light up with a sparkle. But then when we text, it seems like a whole different message.. What should i do? Or think? Lol, please help.