That sounds as if it would more than likely be the cause - good call Redneck, even if it doesn't turn out to be the problem, it is a good place to start. As the oil is clean, it could easily trickle down and be almost impossible to see until it starts collecting, on the fins in this case.
I hope it was only a temporary apparition and it doesn't re-appear Warbird? Indian Bob, anything further on your oil leak yet?
