Sounds like it could a couple of things. Either the graphics within your 360 are starting to lose their edge or your television is showing signs of age. Could also have been an odd read on your disc that happened for a moment.
When it happened I quickly switched to cable channels and they were fine. But when I came back to my xbox 'channel' it was happening again, so either my Xbox or the game. The thing is this game has a lot of visual bugs. One time one op Firestorm the road
had a red patch 50ft by 50ft.
I'm not sure though because my xbox is pretty old and it gives me the "couldn't read disc" error when I initially turn it on some days.