Oil in distributor

[wagons at sover.net]

I haven't checked the archives-- forgive me if this is a common finding. I
had poor after-rain starting, with a low-speed or under-power miss until
the engine was thoroughly warmed, so I replaced the (45,000 miles on it)
distributor cap. I found a small amount of oil in the cap, that had
softened the black outer casing layer, allowing the cap to distort.
Obviously, a horizontal distributor like ours must have some kind of a
shaft seal, and I guess mine is leaking a just a little. I guess if it
happens every 45,000, I am not going to worry.

Anyone seen this? prognosis?

Dan Wing