i had that problem with my valve cover..did u tighten everything evenly?
n its gotta be really tight..there was some oil in where the top screws go..
i just took a papertowel and soaked up a lil bit of oil so i can get it to sit all the way down..
oh..and when i put my vavle cover back on..i put some high temp silicone gasket between the rubbergasket..sealed pretty good..
its only leaking out of the top bolt right? just clean it up and tighten good..problem should be gone..