Volvo AD41 oil pressure.....cause to worry?

[dpb]

First season with boat and up till now both engines showing pretty much identical healthy oil pressures.
ie over 60psi at start up and and only dropping to about 45psi when hot at tickover.
One still does.
But the other has changed behaviour.
Now goes to just under 60psi at start up.
When warm tick over is now about 30psi and doesn't hit 60psi till I get 2500 to 3000rpm, which it holds firm. It use to go straight to 60 as soon as the revs rose above 1000rpm but not now.
Technically it is still in spec (30psi at tick over and 60 at full revs) but that dont stop me knowing its changed.
Temp is still normal.
I have had cars in the past with 'proper' oil pressure issues and they behave different, in particular the tickover pressure has fallen well low such that they barely register. This seems different.
The issue started it seems between one week end and the next and was not gradual.
Oil and filters are a few hours old. No oil being used by the engine and no leaks noticed.
I will check the gauge by switching them but am thinking maybe the pressure relief valve...or is it valves. Still trying to work out exactly where by the filter they are.

Any thoughts appreciated!

 

[volvopaul]

There are 2 oval shaped end covers held on with two ten mm bolts, one is piston cooing jet valve other is main relief valve. They are to right and left as you look at the filter housing below oil cooler.

 

[dpb]

Thanks for that, see where you mean on the volvo exploded diagrams. They look like the valve on my espresso cofee machine, trouble is I have had that apart a few times and it still leaks so not encouraged!
I will remove and inspect over the weekend.
From the diagram though it looks like by the time I have removed them it wont be possible to see if they were stuck open or not. Still, I guess just fiddling with it might sort any issue they have.