Knock cold idle

I recently started hearing a knocking noise shortly after starting my 07 LBZ 120K miles (Florida cold start). It sounds like its coming from the top end and it sounds like a small engine rod knock. It goes away just above idle speed and when it warms up. I do not hear it at highway speed or under a load. The oil has been changed recently and is at the correct level. The oil pressure is about 40 psi at idle and 60 psi at speed. Other than the knock it idles/runs fine, no skipping or loss of power. Ideas? Thanks in advance.

Is it possible that a valve is out of adjustment? When I replaced the head gaskets on my '05, the valve train needed to be adjusted to spec up on reassembly. I can see where one or two might be a bit loose when cold.

I guess its possible, it sounds a lot like the older Dodge Cummins.