Oil pressure too high?

Ok, so the weirdest thing happened tonight. Well, ok maybe not THE weirdest but it has gotten me thinking and can't figure it out. . .

Driving my '66 Cuda with a 1974 stock 360 4bbl in it. I've put about 4,000 miles on it so far this summer, changed the oil and filter maybe 800 miles ago. Used my good trusty Rotella 10-40. Have had no problems at all ever before.

Went out for a drive tonight. Usually the oil pressure is a little over the "half way mark" on the gauge when its cold at idle but then drops down to just below the half way mark. As she warms up at cruise, 50mpg 2,000rpm it sits right about the 3/4 mark, it has never gotten above that unless I'm on the highway going 70 or 75. Ok, getting a little rambling, but it is 1am here and I had a final exam this morning ;)

Basically, when I went out for a drive tonight the oil pressure was staying in the high 3/4 tick area at idle after it was warmed up and just cruising around at 30-40mph it was pegged, the gauge was dam near maxed out! I dont really know whats going on. I figure too much oil pressure is better than none but Hmmm . . . at a couple lights it would get back into the "normal" range but as soon as the revs got over 1,000 pressure would be right back up there too high.

Before everyone says anything, yea I know 10-40 is a tad thick but its been above 70 here and I drop to thinner stuff when it cools off so I dont think it has anything to do with that, plus it was about 80 here today.

What the heck would cause the oil pressure to spike like that and stay spiked? For snickers I may drop the oil filter tomorrow and see if anything got stuck in it . . . or if some sludge broke loose? Thats about all I can think of, she runs like a top
any other ideas?