Breather for AOS Line?

[Lapister]

So, after replacing the Rear lower trailing/Track arm on driver side I was noticing a bit of oil trickling down the left side of engine. Pulled the front engine cover and there looks to be what looks like a breather orifice where the Aos hard plastic line connects to engine. Should this be normally dry and just vent? It looks to be mostly oily vapor that just slowly wets the engine. Asthetically not pleasing to see. The object in question is the round opening with cross in the middle.