The purpose of that hose is for the engine to pull fresh filtered air into the engine. THE positive crankcase ventilation system(PVC) This is going to the front of the valve cover. On the rear of the valve cover there is a hose that goes to the manifold. The manifold is drawing air from the engine valve cover. This is the in / out process of air because as the engine runs there is that movement of the pistons and it does build up some pressure. Check the manifold side of the hose/ pull it from the manifold and see if it has oil. In reality it probably has a film of oil there too. You’re just making sure you got air flow, if that hose is cracked or has a leak it’s not doing its job as well as it should. Wipe everything clean, monitor it to see how it looks after a few thousand miles. I suspect it’s really not much of a problem. One thing on y to do list is to mount an oil catch can on the suction side hose going to the manifold. Allows you to have the benefit of the system but provides a “catch” container so the engine does not ingest the oil keeping the intake valves a little cleaner.
