It is a good idea to make some oil catch can between the breather and the airbox. :devious
Then it will not allow this small amount of oil to get inside your chambers any more.
This oil helps to create carbon build up inside...
If you take out your TB's you'll probably see inside on your intake valves carbon build up.
If you take out the rear cilinder head cover, you can see how the breather is made. it is just a "hole". It is normal to have some oil on your airbox.
But just as said, take care to not over fill the oil tank.
:thumbup:thumbup