LS oil pressure

[2014sierraAT]

I have a 2006 6.0. A couple weeks ago I noticed at cold idle my oil PSI was fluctuating between 20-40 lbs( not gradually fluctuating, needle basically bouncing. Everything sounded fine, gave it a little gas and it come on up to 40 lbs, which is what it has idled at since I got the truck. So either the engine has done this since I’ve had it and maybe I just never let it cold idle long enough to notice or it’s something recent. Either way, what does this mean? I would think 20 lbs would be ok at idle I just don’t know why the sporadic jumps are happening.