Recently I've started to notice my oil pressure dropping further and further. On a cold start up I have good pressure, right at about 40 or a few notches above. But once the truck starts to warm up, it drops down to maybe the first notch or two. Accelerating back up to speed I have good pressure, but once I reach cruising speed it's down again. Cruising at 70 on the freeway, like I said before, it's sitting 1 or 2 notches above the red. Now I just rebuilt this motor 10k miles ago, so it's still brand new. I never did replace the oil pressure sensor during the rebuild, Could the sensor be going out?