Oil where it shouldn't be?

[Hammer]

One problem I noticed was during the changing of the plugs and wires. On cylinders 6, 7, and 8, when I removed the old plugs there was oil on the spark plug socket. It looked like fresh oil, which was just recently changed. The plugs themselves looked fine, as did all the other plugs and the old wires. The problem seemed to be confined to these cylinders.

First thing that comes to mind is possible blow-by in the cylinder\s...