My 2004 model does the same thing. Is in the garage so is not causing any concern.
After looking at it a couple weeks ago I determined that the slot for the stroke measurement indicator (dots) is the culprit, and the longer the stroke the more fines. I noticed a larger pile when I increased the stroke to max a month or so ago.
Sounds like the catch pan idea is the only solution, aside from giving Harman hell.