anyone else have this happen to them?

playing on lighthouse, shot an enemy in the head 3 times and got a hit maker each time just to have him shoot at me and kill me.

Yes, as frustrating as it is. There are many factors at play here though. He may have been using armor boost and sniped you in the head. Or could just be lantacy i.e. like playing Black Ops Multiplayer (It's a common issue there too on core).