Cossie paranoia!!
Stop worrying, the gauges are notoriously inaccurate, and vary hugely, the fact the car is doing what it should and not overheating etc shows it's ok, it is even within the NORMal range anyway, mine sits around the top of the N all the time sometimes in traffic, when the fans cut in it drops 3C to under the bottom of the N, my fans come in at 95C and go off at 92C, as I set these temps on the ecu.
The amount of movement for just a tiny temp increase is totally disproportionate, ie just a few C's makes a massive difference, when up to temp, it just looks a lot worse than it is.
Certainly doesn't show/sound anything to worry about.
tabetha