Overheating at low speeds

I have a 3 speed auto '89 Corolla hatch and am having the opposite
problem than most with my temp gauge. When I'm idling or driving at low
slow speeds the temp gauge maxes out to a centremetre past H, but
there's no effect on the car at all, and when I cruise, even at hgh
speeds, the temp goes down to very normal. While I'm quite certain that
the car is in no way overheating, it is still disconcerting to look at
the gauge that high. Does anyone know anything about this problem? Is
it common? Does it matter?


Thanks for any help

Neale