Be aware that while the "C" engine is speced at 40 psi at 1875, that is really a minimum - most run more like 50 psi "fully warmed up" and 60 is not unusual at higher RPMs. The 1991 "L" raised the relief so the spec was raised to 60 psi at 1875 rpm.
These are based on 5W30 and an engine that has been run for a while. Colder and different weights will read differently.
If you start from idle and raise the rpm slowly when hot, you should see a hitch in the needle when the relief valve opens.
Unlike a gear pump, the "Georotor" oil pump used in the 3800 does not have large pressure changes over the RPM range.
Other than dropped cam bearings in some '90s (and the 19 psi max oil pressure is obvious) I have heard of very few oil related problems with 3800 though the gauges are notorious in being inaccurate and changing (why the factory says to use a mechanical guage).
The other thing to be careful is to use the right sender - a "C" sender will read 20 psi high on an "L" dash and verse the vice. Basically though if it is running good you should be more concerned with changes than the numbers.