Facebook stalker lol what should I do about this guy?

A few weeks ago, I went to my friends sweet 16 and met her friend Adam from church. I'm in 10th grade and he's in 12th. We hardly talked, be he added me on facebook and has been talking to me a lot. He messaged me and we had a regular conversation, but now he's starting to get a little overbearing. Whenever I post something on my friends walls, he likes the post. A few times if I was online in the morning before school, he'd message me asking if I'm school yet and what I'm doing. He just always messages me and IMs me now, wanting to know every little thing I'm doing and who I'm hanging out with and what not. If I say I'm hanging with friends, he wants to know their names, who they are and everything we are doing. A little while ago, we were having a normal conversation over IM and all of a sudden he told me I seemed a bit off and if I was tired or what was wrong. I thought this was weird, cause I didn't even do anything and when I asked him why he thought that, he said I just seemed to be acting a bit different. He asked me to hang out twice. Although he seems like he could be a nice person, I don't think I would want to date someone who already wants to know everything I'm doing. It seems strange that he's acting so overbearing when I hardly even talked to him at the party. What should I do? I don't wanna be mean, but it's just a little strange lol.