GE likes to keep all tech info a secret so I cannot say for sure what is going on.
My guess is that the thermostat is opening correctly.

One possibility is that due to the thermal mass etc. of the heater assembly there is always a temperature overshoot even if the thermostat opens at 145.
Looking at the back of the thermostat in the parts it looks like it re-closes at 140.

Another possibility is that this thermostat is not controlling both elements so depending on the temperature setting the other element may still be on.

Below are some sample wiring diagrams with typical GE wiring for a couple units.
http://www.applianceaid.com/diagrams.html
Check in the control console for the wiring diagram. They often store one in here.

Another possibility could be that you have a grounded element so that element is not controlled by the thermostats.
Check the heating coil.
Unplug the unit and both wires to the coil.
Check it with a meter, should be around 12 to 20 ohms.
Then check from each side of the coil to the case/frame, both should be infinite ohms (open). If not the coil may have sagged or broken and is touching the case. This can cause it to run all the time.
Then do the same thing with the other element.

Vent is free of obstruction, lint trap is cleaned.

My mother said that she thought her dryer was running really hot. I monitored the air flow coming out of the dryer exhaust with a meat thermometer for about 10 cycles. It would rise up to between 170-190F and then drop down to 90-100F before cycling again. I think that actually is a little more hot than it is supposed to run. It has two thermostats on the door... a 145-15 and a 135-15... it shouldnt be going to 190F should it? (it also has a high limit 258-50 thermostat and a one-time use safety thermostat)

All of the thermostats measured less than 1 ohms, but the 145-15 thermostat had a charred terminal. I suppose i am going to replace that thermostat, even though the label isnt charred and it measures less than 1 ohm.

So:

1. Should the dryer be reaching 190F with these thermostats?

2. Since it is cycling, that means a thermostat is working... why is it letting it go to 190, if they are rated for 145 and 135?