Yeah, shady dealer. My dealership denied the work too, I actually had to have my lawyer write them a letter to get them to even look at the car.. regional rep came by and said it is definitely covered.
The rear fender is an awful design, I'm surprised it doesn't rust even more than it already does for us.
Don't expect the warranty work to hold up, it's good enough to maybe get you by until the warranty is over so that it isn't their problem anymore (pow)
I'm thinking of having a body shop actually repair the rust (i.e. sand the rust on the inside instead of just repainting the outside like the crap dealer shop did), roll my fenders, and fix all the bubbling paint.
The rust that Mazda doesn't have to cover is when the sideskirt rubs the paint off on the lip of the rear fender (as it has on my car over and over. Since they were in there anyway fixing the other rust, they covered it for my car. They even pulled the sideskirts and installed a thin rubber gasket between the sideskirts and the body. Sadly that wasn't enough though, it's chipped again.