YB,
I would be checking all obvious places for leaks like rear of rocker cover and side plate first just to make sure its not coming from another spot first.
The rear main seal was discussed recently by another fellow who replaced it in the car. It was bad enough doing it on the engine stand where I could use a broken crankshaft to seat the seal and clean up the edges where the caps joined.
If it is the rear main seal and you can live with it I would wait until you had to pull the motor out before fixing it.
Cheers ChrisB
