i have a few NS boards and i have hit lots of shit, rode over rocks @50mph - none of them split like that.
i will be shocked and disappointed if they don't take care of you on that one.... that said i can see how they might say "its your fault, too bad" - if they do then get a good 2 part epoxy, mix it up and drip it in there or even better shoot it in with a syringe, and clamp it while it dries and cures
still, its NS.... i hope in my heart of hearts that they would just replace that. if you hit it hard enough on something to truly destroy it they usually look way more violent than that. that looks like a delam - delam is the epoxy's fault - manufacturing defect.
get the hell off my lawn.