olblu49, it's been my experience that just about any engine will have higher oil pressure when first started. After it reaches operating temperature it will decrease somewhat, how much would be depending on oil viscosity, engine wear and a number of other factors.
I think Your heading in the right direction with checking the accuracy of Your current gage.

"All right, they're on our left, they're on our right, they're in front of
us, they're behind us...they can't get away this time"

Lt Gen. Lewis B."Chesty" Puller, USMC