It is possible your cooler might not be doing the job as well as it should. It might do you some good to thoroughly clean the fans on the heatsink of any dust on there. If you really want to go to town then remove the heatsink, clean it and reapply a fresh batch of thermal paste (arctic silver 5 or arctic cooling MX-2) and reseat the heatsink on the CPU. Either that or get a third party heatsink altogether for better cooling. I'm not well versed in how hot the C2Q's run idly etc but 60 degrees seems awfully hot (my core I5 never goes past 45 on 100% load in prime 95) so perhaps there has always been a contact issue with your heatsink and its taken it til now to manifest itself.