rusting...looks like chicken feet

[hocky1]

Got 10 spots on the roof around the sunroof, maybe caused by flying stones. A slightly raised centre with veins going out in all directions from this spot. Waited 1 year to see if they will grow larger and found they have now. Have scraped the paint to metal and treated with rust buster and wonder if anyone have this happenning too. Mine is a Euro C180 with original paint as far as I know. Have fixed up with original colour paint filling up the depression caused by the scraping and sealing with polish and wax. Will this last for a few years? A roof repaint was quoted at about A$450 on the cheap side and A$1500 on the killing end. There is no damage to the roof metal skin i.e. no rust through or holes.