Slide Out Structural Issue My Fault or Warranty ??

From what I understand about slide outs is if it is raised at the edge when retracted you are not supposed to step on it as it may damage some of the rollers or whatever it uses along the edge. It should not have caused the issue you stated based on my knowledge. Different makers have different instructions and construction techniques. If it were me I would take it to them and tell them it broke. I doubt it will be questioned as to the circumstances if your dealer is worth his salt.