Just got my car on Saturday!

It is in the high 90s here in Texas. Both of my side (rear view) mirrors stay hot ALL the time when the car is on. The manual says: "The exterior rear view mirror heating is switched on automatically at low ambient temperatures."
This would seem to indicate that they should not even be ON now, and that they should be OFF because the temperature here right now is a very HIGH ambient temperature.
Any ideas?
Thanks.