Oil Pressure Question

[C10agent]

Hey Guys,
So I am a bit of a newbie when it comes to the engine..........okay everything. So I didn't trust the stock gauges so I hooked up a three gauge autometer knee knocker setup. Good thing is it doesn't overheat like the old gauge said. But, the oil pressure is throwing me off. So when it first started up and it is cold it is around 60 and the needle will bounce about 4 psi when idling. I let it run about 20 minutes and it would slowly lower until it ended up around 30 psi before I shut it off. Is that right??? I am freaking out that I have an issue with them motor, any help would be greatly appreciated. Thanks, Neil