The funny thing is that you failed to give an explanation to the problem he has, you just comforted him that his cpu temperature is safe -for now- and you are accusing me of not thinking before answering.
For all we know it could be the thermal paste drying off or a problem with the VRM, causing voltage spikes.
Maybe you are the one who should think since the poster has stated that he didn't experience these temperatures before and that they have been rising for about a month.
Contradictory you say that 10 degrees from 51 to 61 the max temp are far apart while 11 degrees from 40 to 51 is a slight increase in temperature.