Is this normal?

So I heard a weird engine noise a week or so ago (http://mbworld.org/forums/c63-amg-w2...rt-up.html)and it never came back, but I've been checking my engine bay regularly after each time I drive it to see if anything looks amiss.

Coupled with the recent news of a class action on the M156 engine and I'm extra paranoid:lol:

I had a service A done last week after the noise happened so I'm not sure if that is relevant, but I thought I might mention it. Also my car has 4000 miles on the clock and it is 13 months old. Its never been in the rain and I've never washed the engine bay before, so it is a fresh from the factory as possible for a 1+year old car.

So my question is, I noticed some oily residue on the inside of the pulley marked and also on the top part next to the belt (its about a 1/4" wide piece of metal) as marked in the picture. The belts look fine and no oil appears to be on the belts. And I couldn't see any evidence of oil fling or anywhere else in the engine bay. The tray below looks dry as a bone and spotless. So my question is, is this normal? Did the tech oil this during the Service A? Is it just left over grease from when it was built? None of the other pulley have this on them.

Please tell me I'm paranoid and its normal:angry-banghead:

http://www.60-130.com/images/importe...9/Slide1-2.jpg

I'm not going to click any MBworld links unless I have to but what does the noise sound like and under what circumstances did it happen?