Corrosion on Hatch Fasteners

I have white corrosion on the fasteners on the rear deck where the hatch is. (Open the rear hatch and you'll see about a dozen of these screw-like fasteners.) At first, I thought it was some sort of wax buildup from my dealer's vehicle prep (it's a new 04). I removed them, scrubbed them with a soft vinyl brush, but couldn't seem to get them clean. After reinstalling and waiting about 4 or 5 days, the corrosion returns.
Is there a way to keep these clean? Another question is: is this normal or is it a material defect that I should report to the dealer so they can be replaced?
Thanks for your help. :thumbs: :thumbs:
:seeya




