There is no warranty at Louis Vuitton, except for watches.
Honestly it looks well used, and it most probably hasn't developed this rubbing off of the gold while sitting in the dustbag.
Phone cases — in general – face far heavier use than wallets or bags. We hold them for hours, pick them up 200+ times a day on average. No matter how strong the Vuitton canvas or metal coating can be, it is no match for that use. And it is true for every single phone case on the market (except for a few utility cases designed for heavy outdoor use and only worn by a handful of straight guys).
Apple's own cases are excetional, and even they show heavy wear after 6 months, even in the hands of the most careful. So I would say that this is a VERY good looking case for a 1 year-old product. Really.
I always say that luxury shoes, and especially luxury technical cases (phone, tablet, AirPods, etc...) are the ultimate flex. Not a Birkin. They cost so much for so little time of use. A Birkin can and will last half a century and even then can be completely restores to its original beauty. A shoe (if worn everyday) will get damaged in months, a technical case in even less. And that's it. These products don't last. And cases are even worse than shoes, since technology evolves rapidly, the case will be obsolete with the phone.
So to answer your question, the case looks nice for a year old product of its kind, but you can always ask Vuitton. If you have a very good relationship with your SA and you are a good and regular customer, they might give you a new product as a one time exception (if it is still in production). The other important factor is that these kind of products cannot be repaired. They are so tightly glued and pressed and built into one piece, that removing only the chain is not possible.
