High Oil Pressure

The oil pressure on my 75k mile '73E has always been "good to high", i.e 80-100 lbs when 180+ oil temp and 4-6,500 rpm. I always took this as a sign of good internals.

Recently however I have been experiencing even higher warm pressure, 100+ psi when I rev above 4,500. I use Valvoline VR1 20w-50, and the car has the factory '73 thermostat and front loop cooler system.

My mechanic has confirmed the recent high pressure with a mechanical gauge, and both relief valves were checked and are not stuck, tight or shimmed.

Suggestions? Reading here and on Pelican I haven't found any logic train to follow after the pressure relief valves.

Thanks