Has anyone experienced corrosion of transmission cooling parts?

What is your question?

I experience a transmission fluid leak causing the automatic transmission to slip. The dealer identified the problem as corrosion of the tubing between the transmission and the radiator. They claim that this is due to salt in the air "environmental issues" and therefore NOT covered by warranty. We live in Palm Beach FL and the car only has 18k miles. Anyone have any experience with this or other "environmental" exceptions to Lexus warranty?