Same thing happened to the M6 Touring we have, road debris took out the same panel, part is a reasonable 100ish? Had the dealer replace it so labor......
Edit: Forgot to address the crux of question, no, warranty will NOT cover since it's not a manufacturing defect.
Yes, this is not covered by warranty but is covered under your insurance company. Try to check the price of the item against the participation fee for your insurance then choose whichever is lower.