Ditto to all the above for me too, but I believe that this is because the gauge doesnt' actually report the exact temperature, it is moderated by electronic shenanigans to report too cold, normal or too hot. Ie if the temp rises in trafic, as long as the fan kicks in and takes the temp back down withing a reasonable time frame the electronics will say all is fine and instruct the gauge to sit at 90. If the fans don't kick in and the temp doesn't fall in this time frame or the ecu reports that the fans are in/op then the gauge will start reading hot to warn you.
So I've been told.
My folks used to have a 'cough' vx cavalier and this would just sit at 45C all the time, was normal for this car apparantly.