I agree: It sounds like a valve cover gasket issue. From what I see in your photo you have the chrome valve covers such as I have. The insider surface of those is pretty smooth and if not sealed well can leak pretty easily. It makes replacing the gaskets a bit of a pain, but I use a gasket sealant on the gasket side of the valve covers.
Also, the aftermarket bales are not made of as good a steel as original equipment and when you run the car a good bit and they heat up, they can expand more than original equipment and thus lessen the tension pressure on the valve cover.
Lastly, generally the gasket will stick up above the sloping surface of the inside of the valve cover keeping all the oil from draining back to the head. So, the oil is just trapped there behind the gasket trying to leak between the gasket and valve cover surface. I cut vee slits in my gasket to allow all the oil to drain back to the head.
But hey, why worry about it, your car is just doing a double good job of marking its territory like every good VW does.
