If you have had the car running recently and it seems to run okay it is probably the valve cover leaking oil.
The things I am refering to when I say, "has it been ruing okay", are things like a steady idle, revs up with acclerator, does not stall, does not surge in idle no sounds like air leaks or vacuum leaks when engine is running. The reason I metnion these kinds of problems is that they are realted to vacuum leaks and how they affect the engine performance. This would indicate a leak in the intake manifold as it seals off 2 things, coolant and air. So the symptoms that would follow would be coolant in the oil or bad engine perfomance as I described.
The valve cover is in general more likely to leak than the intake manifold and there would have to be something pushing oil into the intake tract as well because there are no oil seals in the intake manifold. So, I would say they replacing valve cover gasket would do the trick. That is the best opinion I can give you without seeing the car.