This doesn't happen often but I started my 06 yesterday and the oil pressure took a little longer than it should to come up and the check guage light came on for a second. Now when the pressure started to climb you could hear the oil pressurize it seems. The noise stopped as the oil pressure came up. It almost sounded like waiting for the filter to prime after an oil change.
It's an Amsoil filter with about 2000 miles on it.

ive noticed the same thing for about the past month or so , thought it was me at first but it seems to do it once or twice every few days, comes up after about 5-6 secounds when it would only take 1-3 secounds. have baldwin filter on for the first time, usually use gm filter, and running chevron delo 400, same as always. but no check oil light or any noises

Could be a faulty anti drain back valve in the filter. If it didn't do this with the previous one I would start by changing it out. I had the same thing happen once with a Mobil 1 filter. Once it was changed all was good.

I swapped the oil filter the other day and up till today it has been fine. It does it only when it's hot though.
I did have my water pump replaced a month or so ago but don't see it being related but maybe.

My lbz does the same thing. After its warm and sits for a couple hours, fire it up, and gauge won't move for 5 or so seconds. Only does it after you get the motor good and warm.

I've had that happen on both of our LBZ's. Also, i've had both of them on a cold winter start, when you start them, the oil pressure takes a few seconds and then you hear a weird buzzing sound and the oil pressure pegs the gage up at 120 psi for up to 5 seconds or so, the whole time the buzzing is going on. as soon as the buzzing stops, then the pressure goes down to the 90 psi. The '07 hadn't done it until just the other day for the first time. But the '06 does it regularly on cold winter starts. I have no idea what causes the very temporary buzzing with 120 psi oil pressure.

Mine has also done it a couple times when it is cold outside. I have never had the oil pressure message on the DIC, so I assume that it does have oil pressure. I have had mine to the dealer about it, and they put a new sending unit on it, but it still didn't fix the problem. It is just one of those problems that drives me nuts when it does it.

I have noticed that my lbz seems to do it most after it runs for an hour or so and gets everything good and hot. Then it sits for a few hours, fire it up and the gauge reads nothing for about 5 to 10 seconds. I run mobile delvac 15-40 with a wix. I have also run OEM delco filter with the same problems. Truck only has 39,000 miles