I always just use the heat on auto. Yesterday, on my way home from work, I looked over and the fan thing was manually selected (orange indicator around the fan dial). I thought maybe I bumped it (somehow?) and clicked it back to auto.

Today on the way to the office, the same thing happened, twice more.

Am I missing something? If I put it on auto, it should STAY on auto, yes? Not heat the car up then switch to a steady fan speed?