C70II rust on the roof roof element

Today I cleaned all the seals (with rubber pleating agent) and oiled (oil from Volvo – 60Euro). I noticed that the varnish peels off and already form the first rust bubbles under the remaining varnish, namely at the front roof element, at the very front where the roof is lying on the A-pillar. I suspect three causes: 1. too violent “smiling” of the roof element on the A-pillar at closing 2. the seals were very brittle and dirty – this scratchs on the paint and “smokes” it permanently away 3. Misconstruction – in my eyes a place so burdened is better protected (dicker rubber, otherwise what?) My car is year 2006 and now has 205tkm down. does anyone else have this paint/rust phenomenon? And above all, what can you do against it??