Hokie and Slim both bring up the first places I would start.
Does it smell hot, popping/creaking sounds as it cools? Smell antifreeze?
I would add - pull wire off temp sending unit, clean connection, an make sure sending unit is tight.
Get an infrared thermometer and check top/bottom radiator hose temperatures with that.
Also, put a hand on the top and bottom radiator hoses to see if hot, and also feel fluid filled.
All are just to verify it really is hot, or just the sending temperature sending unit running afoul.
Mine acted "funky" a year or so ago, and simple cleaning of the spade connection on the temp sending unit seems to have fixed it. Don't think it was ever hot to begin with.
Best wishes!