Is it normal that i jerk off to girls i know?

I usually just load up a picture of them on Facebook then rub one out. I'm not a creeper to them or anything. I'm just doing it to get off cause I find them attractive. It seemed weird for me to do at first, but after a while it became pretty regular. It thankfully hasn't made talking to them at school awkward as a result. Anybody else do this and is it normal?