sounds like a sticking thremostat with the change in temp, between the two areas of coolant, as long as it had plenty of water and it didnt show in a overheating on the temp gauge it should be ok, check for blocks in the system rads are common, and also maybe a low temp thermostat might be a good idea to help the car cooling, only one way to find if its done damage, fit a stat and run and check it regually, its cheaper than taking the head off staight away