Confused 16 yr old girl... abuse or no?

My bf and I are both 16, going on 7 months.. he is an all around great guy, doesnt get jealous, respects everything about my life, job, friends (both guys and girls) family.. Ive just noticed one annoying trait he has- occionally, we will be laughing and cutting up and he will lightly slap me somewhere, the stomach or on the leg and think absolutely nothing of it. Ive asked him about it and he is truly baffled and says its something he's always done, its a way to flirt and I do know in the schools today guys and girls hit each other all the time in mock fights, etc. This past Friday night tho, I think it became too much for me, he hit me in the back with a basketball as I was walking away from a game, then shut a door on me bec I was trying to go inside and slapped me on the leg when I put too much chapstick on him.. he says he was joking about all of it.. Im so confused.. your thoughts?