You don't knock your skis together on the lift, do you? That will chip away at the topsheet like it's nothing eventually exposing core. Once the open core is exposed to water, it will start to deteriorate and get really soft there, sometimes altering the camber.
Maybe it's not your fault at all, not saying it is. I have had tons of kids bringing their new stuff back to the shop I work at for warranty issues, and 90% of them have been knocking their skis together really really hard on the lift for some reason