I checked my Radiator Overflow last night and the level of coolant was fine. Today while driving to work I spent about 2 hours in traffic that was barely moving on a very hot Louisiana day. I checked coolant a few hours after getting to work and the level in my Radiator Overflow was right on minimum. So my question is has anyone experienced low coolant in Radiator Overflow after sitting in extended traffic?

I have not noticed a leak and there is no coolant in oil or transmission fluid.