I'm hoping I can get some help working through this and figure out once and for all if I'm overreacting or not.

Possible trigger:
I need to know whether or not something that happened when I was a teenager was abuse, simply creepy/inappropriate, or an accident.
When I was in my later teens, I was laying in bed on my stomach with a headache. My father came in and said he would give me a back rub. I wasn't wearing a bra. He pushed up my shirt in the back so he could rub the bare skin. While he was rubbing my back, his hands would slid down over the side of my breasts and he would rub the back with his thumbs. He would move his hands and then move them back and keep them there for a little bit while he rubbed with his thumbs. He asked a few times "anywhere else?" Meaning did I want him to rub anywhere else, (maybe my shoulders or hands or something?) I was feeling awkward and just said in a normal voice "no, it's ok".
Once he stopped he left the room and I just thought it was so weird. Back rubs were normal growing up, but not like this with the contact on the side of my breasts or the bare skin.

I've never given anyone a back rub like that. Although his hands were completely on the side of my breasts, is it possible he didn't realize it?
Is it normal for a father to rub his teenager daughter's back by pushing up her shirt in the back?
Was this just an accident most likely?

Thank you