Thank god I found this topic.
I'm on the xbox 360 and noticed this last night. It wasn't until I switched to the save screen and noticed that the mark suddenly disappeared, only to reappear when I left the save screen, that I knew I wasn't crazy.
I even went to another profile on the xbox and started a new game to check; spot was still in same location on screen, but disappears on save screen. I did check my tv and it doesn't have a dead pixel.
Wonder what causes this strange bug.