Hi,
there is always a chance that the gauge got haywire or just a bad ground.
If you can, try to measure the temperature at the thermostat housing.
There are low cost infrared thermometer, perhaps at a Harborfreight near you.

If you measure about the same temperature as indicated by the internal gauge, then it is time to investigate more.

Careful, in most cases I know of, the head gasket(s) was on it's way out.
Another check one can guestimate, but is probably too early in your case, a builtup of grey/greenish gunk on the oil filler cap could indicate water contamination withint the motor oil.
This usually goes along with higher coolant pressure and the pressure release mechanism at the water reservoir would indicate that. The level in the reservoir, could be higher than usual.

__________________
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Norbert