I have been wondering the same but on my cummins. its a 98 12v 220k i have only had it about a year but cold 80psi warm is 60 under load but around 30 at idle. seems more noticable this summer than through the winter. this is a mechanical gauge, the factory one doesn't work

 

I recently installed a 4bta with ~113k on the motor, in my truck and with a mechanical gauge that reads to 100psi. When cold and idling it reads right at 100psi after a minute or so it goes down to ~90 which is when i start to drive it. When warm going down the highway it reads 75-80psi. The only thing that concerns me some is that the psi will go down to 65-70 when under a hard load. ie: going up a steep grade for a couple miles fully loaded. But then the pressure will go back to 75psi when back on level ground. at idle, warm I'm at 45psi.
Not sure I answered your question but interesting your pressure is lower then mine!

 

How were the bearing clearances?? Did you replace the pump,or reuse the old one?? What weight oil is in it??

 

Had 0.003 clearances but bridge reuse the pump. I figured those things were industructuable. Running 15w 40 of course and I changed th oil since

Should I be concerned. Should I be worried about damaging anything if I continue to run it and I maintain over 30 psi.

 

Cummins spec:
The minimum allowable oil pressure at idle is 10 psi
The minimum allowable oil pressure at rated power is 30 psi
You can't expect two different engines and two different oil pressure gauges to be the same. Now if you were to swap the same oil pressure gauge (including the sending unit) between the two, that would be a better comparison.
Your readings are within the limits, but are a little on the low side from what I would expect on a newly rebuild engine.

 

My two engines (both warm)

P7100 6BT: 20idle/60 running
VE 4BT: 30 idle/ 55 running

 

Did you inspect the main oil rifle pressure regulator at overhaul?
it is the most missed item on the list.

 

My truck is at about 30psi warm idle and about 60psi when cruising...