Feel around the surface of the laptop, does any spot in particular feel exceptionally hot? Feel the ventilation, is it extra hot? Is it expelling air at all?
I suggest removing the back access panel on the laptop, if it has one, then carefully fire a can of air(or compressor with appropriate fitting) into each ventilation notch individually until dust ceases to fly. This should rectify most of your heat issue, if not entirely.
While sensors can often be inaccurate, it's still a safe practice to clean these guys out from time to time.