only other rusty punto I have ever seen was a punto van in white (naturally) and must have taken a shunt up rear and had a new boot lid, but obviously not a galvanised one as it was almost completly eaten through.
The only bit of rust on mine is a 2"x0.5" strip on one of the battery straps. Not bad going for 6years living actually by the sea, and 1year of living 3miles from sea (prev owner, and me).