Whats everone working on?

I took the Ol'Dodge Dart out for a quick cruise to turn the wheel bearings over and get the rust of the brakes. (It had not been driven for 6 months) By the way, I put a small, solid core battery in the old Mopar case and it still had power in it! The 340 started right up! OK, on with my story. I drove the Dart about 25 miles and decided to fill her up just before I put her back into storage. I got premium for $2.17/g and when I started her up at the station, NO OIL PRESSURE! (It is full restoration so all I have is the stock oil light) I only had 3 blocks to drive back to the my shop. So I went slowly back. I did not hear any lifter noise or rod noise. When I got her back, I checked the sending unit and the wire was still connected. I relaced this unit when we rebuilt the 340 5 years ago. I have driven the car about 2,500 miles since the rebuild. I know I need to put a mechanical gauge on the engine, which I will do. But, what could have gone wrong? I kicked her down into passing gear and she shifts a 5,200 rpms. I did this after she was warmed up. I drove her for about 30 minutes after that. She ran well and showed nothing until I started her at the station. Any ideas?