this car was well taken care of and i drove to work the other day and smoked a cig.w/ac on, as always, and bofore i was done it was dinging saying coolant temp. so i shut off car and waited 2hrs. Then tried to add water but was full. So drove to the store and back and the upper hose on radiator was still squeezable after warmed up .... should it be or is the thermostat sticking. today it went above half but back below half once i started moving and never did before. owned car for 10 months thanks