Guy question... Please Help?

Okay, so there is this guy I like and my friend and I went over to his house to chill for a bit. It was really fun and then when it was almost time to leave me and him were laying on his bed and I was lightly stroking his back and Stomach (Which is proven to make someone horny). He started getting a hard on after I started that. He then fell asleep and I tried waking him up by tickling him and he got mad at me kinda :\. Anywho, when I got home I talked to him for a few minutes and he said he wasn't getting a hard on cause of me and that he just gets "Random boners". Am I overreacting by getting a little upset by this? What should I do?