Guy came in his pants

Sooooo I've been seeing this guy for a while and he's always telling me about what he wants to do to me in bed. I finally take him up on his advances and we get into a grind session fully dressed before we actually get into the actual sex. And he like came in his pants!!!! I know it happens but I've never seen this before. I was like trying not to act surprised or even upset but has anyone else had this happen and how did you handle it? I was a bit disappointed because of all the smack he talked about what he would do or could do to me and he came before we could do anything.