It is not hard to spot something a little strange in the image shown here. That white layer on the inner rim of the Aprilia RS-GP air vent is grease. A simple yet effective way to catch any dust or debris before it gets into the air box. A remedy also used in car racing (rallying for example where the racing takes place off-road) to prevent dirt from getting to the air filter.
It is not so common to see this in MotoGP though, and the fact that the Noale guys have done this means that the Austin track must be very dirty. The potholes are a well-known problem, but there is also dust and dirt on the Texan track. In the land of the barbecue, the grease is not just that of the bacon sizzling on the grill.