It could be short cycling due to dirty coils or a bad condenser fan motor. GE says that the condenser never has to be cleaned and that when the condenser gets dirty it will not affect how well the refrigerator cools but I am not sure I entirely believe that but I know that it isnít as important as it was on the older GE models. Make sure the fan near the compressor is running. If not this page should help http://www.appliance-repair-it.com/refrigerator-fan-motor.html
Since it is a variable speed compressor I donít really think the fan is the problem but it wonít hurt to check it.
This model also has a variable speed compressor so there is also a chance the compressor is running on a slow speed when it should be running high. I havenít seen this yet so I donít know what would happen if this were the case but I assume it could do what yours is doing. A bad thermistor, main board or inverter board could cause this. This model is also a dual evaporator model so it has a three-way valve. I donít think the valve itself is the problem but the board could be activating the valve too often. A bad thermistor or main board can cause this. Since thermistors are inexpensive and can be causing your problem in many ways I suggest replacing the two thermistors in the freezer and see what happens.
I would access also the fresh food evaporator and see what it was doing. See if it is frosty all the way. Note that you may have to check it for a while because it goes though defrost cycles very often so when if you access the evaporator when it is in the defrost cycle there will not be any frost on the coils (assuming defrost is working properly).