I removed my airbox to get to the valve cover the other day and discovered oil splattered in the airbox. What could cause something like this?

 

too much oil

 

^no its actually pretty common. crankcase breather.........just like blade said

 

so is there anything i need to worry about being damaged? I did notice it was too much but I thought this bike mechanic knew what he was doing. He is the one that added more oil than i needed. I'm done trusting these fools.