Low Oil Pressure????

[mark300d]

Hello everyone,
I had a strange problem on Tuesday, at least I think I did. I was going on the freeway and it was congested. I had to drive slow, 35 and below, for at least 25 minutes. Then the trafic cleared up and I took my 123 to 70 or 75 mph. I looked down at the oil gage after a couple of seconds and noticed that the oil pressure was at 40 psi, and not pegged as it should be. I imediatly droped down to about 55 and the next time I had a chance to look at the oil gage it was back in the pegged position. I took it easy untill I got to school, about 5 minutes of driving.
I checked the oil and it was right at the minimum.
On the way back I accelerated to 70 and kept looking at the gage constantly. No problem, oil pressure stayed pegged.
The only other strange thing I have noticed is that my oil pressure reading sometimes stays at 35-40 psi when I am at idle. The normal pressure at idle is usually about 20 psi.
Do I have a problem on my hands?
Has anyone experianced this before?

Sorry about the long post, I am really woried.

Mark.