Why did he suddenly stop talking to me?

don't stress, its only been a couple of hours, he could be doing something. You sound like you like him so why don't you talk to him about it? and about the kissing thing, don't get too hung up about it, im sure it dosen't mean anything. Just talk to him about how you feel, hewouldn'tt talk to you all of the time if he didn'tt like you :)