Well, that's where the oil is ending up, but where's it coming from? That's what you'll need to determine so you can fix it. Oil leaks don't usually get better by themselves, they usually get worse. The black cylinder fins look kinda wet so it may be coming from the head gasket. Another common spot is the acorn cover nut for the cam chain adjuster. Hope it's that because it's usually an easy fix (new cap o-ring).