I had the same question. It's so odd that you expect everyone to mention it all of the time but they don't seem to notice because they are used to it...
At first I thought it was a tattoo but then it changed. Maybe he's related to the Ultimate Warrior? My guess is it's either "his thing" or he covering up a scar or both.
I did enjoy the show but Chuck is always talked about but never talks, even if he is in the room.