wait i have a crazy theory. 

think about yourself. you know what you look like head to toe right? well, most people do. 

if you look in the mirror while ingame, maybe its that you recognize its you then from that memory in your brain, the gear gets that image and turns it into your avatar.

im not good at explaining, but do you see what im getting at. I dont have to look in a mirror to remember what i look like, however maybe the mirror actived something in your brain that made you think about your appearance. 

i said its crazy, but since we're throwing out theories, how about that one?