I typically have 'Core Temp' running in the background for a desktop gadget I use. It seems to me that my CPU temp has been creeping up since I got the HP h8-1010 it's installed in. Average temp. was initially around 28°C @ idle (climate here is fairly mild; 70°F or so). Now I'm commonly seeing numbers more like 40-45°C under extremely minimal loads (2% on core 1; 0% on core 2) and reaching 50°C while under less than 10% combined load between the 2 cores. Specifications for this CPU list a max. operating temp of 65°C. Should this concern me or, is the leeway of 15°C enough (keeping in mind those temps are at low stress-level loads)?
65C is for Tcase, what you are looking at is probably Tcore (intended to represent Tjunction) which is usually 10-15C warmer under full-load due to junction-case thermal resistance. IIRC, the TJmax on Sandy Bridge is 95C.
My current room temperature is 35C, my CPU's case temperature is 45C and my CPU's cores are at 59C under full-load.