Radiator overheat on 1991 Nissan Sentra

I don't think i'm to be concerned. When my nissan pintara is idle, temparature gauge rises close to "H" hot and fan's kick in late. Otherwise temperature when driving remains just above halfway. Is there a problem? If there is what might it be.

2 answers
if you change the thermostat, and it still does the same thing, (therm. are cheap and easy to change, and while you do that, a flush and fresh coolant wouldn't hurt.) Make sure that there is NO air in the system. Check for small leaks. The smallest leak can affect the temp. If worse comes to worse, it's possible that the head gasket or gaskets is/are leaking water. let's hope not....
Temperature running in the center of the gauge when you are driving at freeway speeds shows the radiator is dissipating heat well with rush air flowing through the radiator. I wonder if the fan switch is coming in late or more likely the thermostat is not opening correctly. The cheapest and most beneficial thing to do is remove the thermostat and thoroughly flush the radiator.