Thanks for everyone for your responses. I attached a picture so you can see what I mean. See how that thin sheet is bend outward towards my back? This is with absolutely nothing inside of the bag. I can't bend it back and it's always been like that as far as I know. I've always stored the backpack on a hanger in my storage shed. On top of that, the backpack felt really heavy on my shoulders until I switched over to my osprey. Of that I am certain it is most likely a fitting issue even though I already did follow the video that someone here posted. I'll give them a call. Thanks everyone.
Glad I found this post. I just received the R3 I ordered and it’s not flat. Seems to be the same issue as you had, the HPDE sheet is warped. I put it on empty and it digs terribly into my right trapezius. I’m glad to hear they got it right for you, and expect the same. Everything else seems stellar so I’d hate to just process a return.