My dealer is 60 miles from me - about an hour. Don't let that get in the way of you getting up there and getting front and center on this. I've been known to make 2 round trips in a day to my dealer when I'm hot and heavy on them
Who are you talking to at the dealer? I don't know the hierarchy of their business but don't talk to anyone less than the service manager, and maybe, the GM/owner.
Don't tell them you're coming and just drop in. Reference their claim that the Hideouts have "those" kinds of panels as well as some other models. Tell them to take you straight out and show them to you. Maybe they do make waffly slide sides on some trailers....I've never seen one in all my looking. Maybe it was the light, or maybe they were actually flat....I don't know. Yours sure look like they are not bonded to the underlayment or the underlayment wasn't attached to the frame properly.
It may or may not be an issue but remember when the warranty runs out you will own the problem no matter how bad it gets.