It is the stuff from the the train wheels rubbing against the track. It is total BS and they should be able to remove it. It will get worse if left there. I bet the dealer waxed right over it. They should fix it. You could remove all the wax with blue dawn and clay bar it off...

I bet the guy a zaino knows how to remove it but your dealer should do it for you as the condition happens after it leaves the factory.

-marc