Mine does too! I always thought it was just the way I was sitting being different, but no it definitely does this. Happens slowly so that I have to adjust it once every couple days, but it definitely happens. It's the auto-dimming mirror right?
2012 SGM SEL Sedan 303a w/o Nav | Job 1 built 6/2011
FSWERKS Cool-Flo w/ ITG Filter | FSWERKS Stealth Exhaust | 17x7.5 Axis Sport XMX Graphite wheels
Sonic Crew #28 | Rally Revolution #117