Sex on the day after your period ends.

So I got off my period on Sunday morning, and had sex on Monday night and I started bleeding. When I woke up today I wasn't bleeding anymore. It stayed that way throughout the whole day until this afternoon. My husband and I had sex, and I started bleeding more than yesterday. It was as if I actually got my period again. Should I be concerned? Has it happened to any of you ladies? If so, why?