Well, the 2 halves of the track have a loosness to them and allows the seat rails to clack or creak against each other. Probably didn't do it when new, but it's doing it now. I guess that would qualify as wear. Why wear out so soon? Don't know. You would normally think "low mileage car, why did it wear this much already?". MB I guess could argue that it's low mileage because it doesn't get out on the highway much, stays in town alot, meaning more driving cycles, so it has had people getting in and out of it more often, more getting in and out of the car, as opposed to a real high mileage car where a driver sits fairly still in the seat for 3-4 hours at a crack. 2 different drivers could also be a contributing factor if the drivers are of contrasting heights and need to adjust the seat back and forth regularly.
I have heard MB Canada is a little less generous with the "goodwill" warranty claims as compared to MB USA, not that MB USA is a bunch of push-overs either.