Wait a while longer for more responses, it's the weekend and most are out doing weekend stuff and not on the forum.

I would think it would be more a valve cover gasket issue instead of the intake gasket because there really no oil to speak of in the intake or running through it, it could possibly also be a leak in the PCV hose, the PCV is for relieving any pressure/piston blowby from the crankcase via the oil galleys in the head, sometimes there will also be some oil vapor mixed in with the combustion gases/blowby and as it gets removed by excess pressure and also by a bit of suction from the intake, it goes via the hose to the intake to be returned to the cylinders to go through the combustion process again, if that hose is cracked it will/can drip oil residue onto the intake.