Thermistor Increasing Temp  

Thermistor Increasing Temp

I have noticed over the past two days that my hot end temperature reading is doing some weird stuff.  After a print and the hot end has completely cooled down, the temperature reading is slowly (over the course of hours) creeping up.  The only reason I even noticed it was the extruder fan kicked on randomly and I noticed that it was reading at 53 degrees (but still cool to the touch).  I haven't noticed any issues with prints I've run since this, and it seems to cool back down to 25 or so (though always a few degrees higher than the bed cools down to), but then steadily goes back up.  I also tried turning the printer off for about an hour, and then back on, it then read back down in the mid twenties, but slowly began to climb again.  

I'm assuming this is a sign that my thermistor is going/has gone bad, but wanted to see if anyone else had another explanation before I had replace and rewire/wrap the cable sleeve.