Bruising

Okay, so I recently started the birth control pill a little over a week ago. I had sex with my boyfriend on Thursday night and he was grabbing my boob a little bit harder than usual but not too much where I was in pain or anything. But anyways a few days ago I noticed a few bruises on one of my boobs. Which I've never had after sex before. Are bruises anything to be concerned about? I know after starting the pill, your breasts are a little more tender but I'm still nervous seeing bruises on my boob.