My friend, leaks are very risky to ignore. Get it check and get it fix as in P38 gauge continue to show normal untill 119 degree, where as its normal is 100 degree. And at 120 it shows immediately to full extreme right with redlight showing OVERHEAT. So watch carefully.
Before gauge happen to move its a$$ from center, you will notice AC being cutt off (in case it overheat) and so that you can be sure that engine is under stress and pull over and check.