Rear Main Seal Problems?

History
This is Dejevu. Two years ago I puchased this 1998 Venture van and the mechanic had just put in a "new" engine. After driving it about a 200 miles I noticed an oil leak which turned out to be the rear main seal. After much aggrevation and cost to my wallet it was finally fixed. Two years and 60,000 miles later the engine died and I had it replaced.

NOW
My rear main seal on my new remanned engine started to leak after I had put about 1000 miles on the car. The engine was installed in SC and I noticed the leak while I was on a trip in PA. I had several mechanics in PA look at the leak and confirm it was the rear main seal. However, after driving the van back to SC the leak stopped. I took the van to the installer in SC and he says that he cannot see any signs of a leak. Is it possible for the leak just to stop like that? It is under warranty for parts and labor for 90 days. The installer feels that the high side of the crank may caught the seal (not sure I understand what that means) and now everything is OK. Please advise

Any help is greatly appreciated.