At least twice now on a couple of cool mornings I've turned on my seat heater and the light doesn't light up, either on high or low. When I turn on the passenger's seat ALSO (either high or low) the driver's side lights up also. I can then turn off the passenger's seat and the driver's stays lit. I haven't waited to see if the seat heats even though the light is off. I tried it in the afternoon and it worked normally. Any ideas?