I wouldn't do a thing!! Until I verified with some separate tool what the temperature really was! I think you gauge is "off"..

Beg, borrow, buy a temperature gun that uses a laser, that's the easiest that I know of - for taking temps while the engine is operating.

Bring it up to full temp and then measure at the t-stat housing, the hose, the top tank of the radiator and then the bottom.. compare with your dash gauge.