Hey Kadett, I think MProf has a good solution there.
Someone previously talked about an op-amp to check above certain speed, combine the two.
I used to have an Escort that also had the same thing with the needle going up and down a bit (always freaked me out), so once in peak traffic, the temp would climb slightly. It was fine for years like that, until the day the thermostat failed not opening to allowing water flow.
Needless to say, when my eye caught the temp gauge, it has gone right through red on the gauge.
I had to do block and all the arrangement of gaskets that came with.
Somehow I wonder if you had a similar experience.
The moral of the story, a R80 thermostat caused a R40 000 engine to come undone.