Specific VIN numbers refers to the specific group of Roadsters first delivered to the 9 specific States. Of course, many cars were moved into or out of those States by their owners, but the warranty extension/service bulletin covered only that group, regardless of where any may have been later located, or if your non-covered car may have spent most of it's time in a covered State of delivery.
So in reality, it is VIN specific and the "heat & humidity region" is just a smoke screen, they did not even cover the whole region.