I have this problem as well, mine has just turned twelve months old and is white, funny thing is i also had the same problem with my vw lt35 which is white, that i brought new back in 2004, tiny little spots that look like rust around the door jams and over various parts of doors and body panels. Very concerned as you would be i took the van to a vw dealer that deals with body repairs so they could inspect the spots and come up with a answer plus put the problem right (van was only a few months old at this time ) after inspection i was given an appointment to see the vw body and paint rep a few weeks later, the rep inspected the paint work and looked at the spots and asked me if i lived by a railway line that had electric trains running on them, i said yes its about 40yrds from my house where i park the van, thats your problem he said, its not the vehicle rusting its small particals coming off the electric wire every time a train comes by and these particals rest on the paint work surface which gives the impression that the vehicle is rusting. He said just wash the vehicle often and polish out the ones that dont come off with washing it wont be a problem, i went away thinking what a load of you know what, but, true to his word my vw has not got rust probs, so i am thinking this is the same problem with the sprinter as they do wash out and the stubbon ones i polish out.