So I replaced the coolant temp sensor that goes to the gauge cluster. When I pulled it out it had all this white gunky buildup on it. Iā€™m not sure if you can see it in the pic, but it was on the sensor itself and a little ring formed on the threads that looks like a gasket.

Is this a problem and if so what should I do? Iā€™ve never seen it this stuff build up like that. Also when I replaced the thermostat I drained the radiator and the coolant looked brand new. So what gives?