Cascadia, DD15 & High Oil Pressure

I'm driving a 2015 Cascadia with a DD15 & all at once, I am experiencing high oil pressure at startup after its been sitting over night.

Here's the deal:
Ryder lease that we got new June 2014 & had the PM done at 30,000 & Ryder changed to Synthetic oil. The day I picked it up after the PM, it was running high oil pressure at start up but after 5 minutes or so, it dropped to normal & all the warning lights went off. I haven't had a problem since.
Now at 85,000 miles, all of a sudden, out of the blue, for some reason, it has started this again, but now, for the last week, its been every day at start up after being shut down over night. For 5 or 10 minutes it its showing about 70 lb oil pressure at start up. It eventually (over that 10 - 15 minutes), comes back down to normal of about 15 lb at idle & about 40 lb at 1200 rpm. It does shut down but I can start it right back up. It continually shuts down after a couple of minutes & always starts right back up... warning lights flashing etc.

We called Ryder & the service manager said this was an on going concern with these trucks & didn't seem to be too worried about it, but said we could bring it by & they would look at it if we wanted to. We are planning to take it by in a few days for them to look at. Again, he didn't seem worried or concerned as he said its an on going problem with these trucks.

Again oil changed to synthetic oil at 30,000 miles & now with 85,000.

Oil level is full. Not over full.

Anyone else experienced this & if so, any suggestions, opinions &/or remedies?
Thanks for any relevant info.....

 

Hummmm. Ok, lets reverse the question.

The truck until now has never had 70 psi for the past 14 months & 85,000 miles, until the last week/few days. Do I have a problem here? As long as its below 50 - 55 psi, the engine shut down & warning lights never come on. Above 50 psi, the "check engine" & "stop" emergency warning lights come on & after about 2 minutes the engine shuts down. After about 60 psi, the "stop" light starts to blink & within about 30 - 60 seconds the engine shuts down.