Having worked in multiple dealerships, including a Mazda dealership in CT, there seems to be somewhat of an enormous lack of knowledge of how warranty coverage is determined. With Mazda in particular, it is incredibly straightforward. There is a tool called Warranty Wizard on Mazda's internal website. The person at the dealership (service advisor, warranty administrator, whoever) enters the part number that needs replacement- this gives you a labor operation, which is usually something like B1142XRX or something like that. You then put that into Warranty Term Inquiry and that says what the warranty coverage is- basic (3/36) powertrain, emissions, CPO, whatever.
Covering anything beyond what is listed there would be considered goodwill, and would need authorization from Mazda depending on the dollar amount, and Mazda does ask questions about loyalty to dealership, etc. If this part # is listed as covered 3/36, then that's how long Mazda will pay the dealer for replacement of it. Past that, either it has to be processed as a goodwill repair with whatever authorization is needed, or the dealer does not get paid for fixing the car.
There is literally nothing done here that seems like anything out of the norm.