oil gauge...weird

I have a 99 gmc sierra z71 new body style. Just recently I noticed my oil gauge pressure was dropping a little everytime I drove the truck. Finally it stopped dropping but it is 2 notches from the bottom. I hit the gas to bring up the rpms and normally the oil gauge moves...it did not. I checked to see if my oil was milky or low and that is a no to both, everything looks fine my Temp is also normal..any suggestions would be a beauty! thanks in advance.

I would start by checking the oil pressure with a manual guage. If it has normal oil pressure, then you have a sensor going bad. If it acts the same with the manual guage then you have a more serious problem.