A short lived spike should not really hurt you. If its just a quick one I truly doubt the engine is getting that hot. Raise the hood and see if it smells hot, or even lay your hand on it....very carefully. And, as an after thought try a infra-red thermostat and see what it says the engine is doing, as well as check the top tank when thermostat opens up and see what you get.
Take the cap off and put your thermometer down in the neck and see what the water reads when the thermostat opens.... are you sure the radiator doesn't need rodding out? Maybe a good flush job?? Just throwing out idea's....
