Oil pressure please help

Oil pressure is measured at top end of the system. It drops as engines wear. Doesn't matter who built it. Stock oil pressure gauges do not have numerical increments on the screen. Only 9 psi top end oil pressure is required to turn off a oil warning lamp.
Your concern stems from a aftermarket gauge. You don't have a actual problem yet.
If you did, or if they all had the same gauge from the factory, they would all be rebuilt at 60 to 80 thousand miles.