the oil pressure should not drop "as things wear in" and if does it's not a good sign. I wouldn't be too concerned about it at this point as many things can cause the readings to vary with an electrical factory gauge. The gauge itself, any connection problems, charging voltage, sending unit to name a few.
Engine temperature, ambient temperature, oil type, viscosity also can have an effect. Get a mechanical gauge on it and keep an eye on it. twocents beer