I just receive my yearly maintanence on my Carrier Heat Pump. And the technician also checked my thermostat when I told him the auxiliary heat was coming on when it is 60 degrees outside. He said there had been a power spike and had reset the auxiliary heat lockout to OF and he set it back to 35 degrees. How do I check this to see if it has reoccurred?

Get the model number off the thermostat and Google it.
Or just go to the companies website with the model number.
You should be able to download the entire operating manual.
I hope this helps.

If it's a Carrier Infinity Control, press and hold the advanced button until a new menu appears. Look for it.