Yah, Bob's dead on. We have a guage that is nothing more than a mechanical "idiot light". Those switches, as he says, have a checkered history. I agree with that assesment.
There is a REMOTE possiblity of a bad bypass valve which is opening and bypassing the oil back into the sump. This is rare. Generally, it's easy just to replace the switch and see if the problem goes away. If it's doesn't, get a real gauge on it temporarily to test what's really happening (or have your dealer look at it).
Generally though, oil starvation shows up as valve train noise of one type or another. If you're not getting that, you probably have adequate oil.