It's interesting that the rust really seems to happen just at the wheel cover openings. Can you think of any cause-effect for that?
I would try to get some pictures of similar aged cars without the rust, then show that to the dealer. An excellent dealer might do a good will remedy.
This sure seems to apply in your case: "Corrosion other than perforation. Cosmetic or surface corrosion due to defects in material or factory workmanship is covered under Paint Coverage for 36 months or 36,000 miles, whichever occurs first."
Let us know how it turns out.