Ford conundrum???...

Could the oil pump drive shaft have been holding the distributor up slightly before it fully seated? That's a fairly common occurrence in Ford engines from my experience.
You know I was talking it over with my engine builder this morning just because it's such a head scratcher and he's a big Ford guy. We were talking about possibly the roll pin in the distributor gear sharing. He said he'd heard of it happening before and retiring it and then completely losing it about 300 miles further... The next time I get into that truck I do want to pull the distributor. Last night after head scratching and finally getting it running and it was getting late I just left it at that but asked him not to drive it very far...