I just recently installed a K&N panel air filter in my 2010 MCS. The car has about 6000 miles on it now. the stock filter appeared to be fairly clean. when i removed the factory filter i noticed some sand particles in the bottom of the airbox. there wasn't a lot but enough to make my concerned. it was mostly on the left side of the box on the opposite side of the intake.

 

If you'all from the great states south of the Mason/Dixon line, you are infected at birth with the "Great Southeren Drawl".
This allows the people of the South to communicate with fellow Southerener's in a lanuage that can not be understood by those folks of the North.
I would check the air box seal to make sure it is sealing properly.
An old trick is to put a little grease on seal to pick up very fine dirt or dust.
Did you oil your K&N air filter?

 

That's just road accumulation. No worries, I've found much worse. As long as your filter element is in good shape you should have no issues.

 

the k&n comes preoiled from the factory. no need for oil at the moment. the sand debris wasn't a lot, just a little bit in a few spots. I tend to worry more than not.

 

When my Honda CBR wouldn't start after being in storage over the winter, I started to troubleshoot. I checked the air filter, and when I cracked open the airbox... it was full of bees, wasps, flies, and dead moths, not to mention a ton of sand and dirt. God knows how long I'd been riding around like that.

 

in any of a Mini, lots of Audi's, Toyota and Chrysler minivans, you name it.

Shows you some of the reasons filters are used to start with; when mounted horizontally like the Mini heavier stuff just naturally drops down into the box.