Ya gotta remember how they get here. The bulk storage units the size of a semi trailer are the standard of the shipping industry. The thing is filled with stuff from China and loaded onto a ship. At 8 feet tall, the stuff on the bottom gets squished and it certainly gets hot as it sits at the dock warehouse awaiting the clearance to move to the merchandising chain.
I know, that's no excuse, but that's why the things are warped. I would guess that as the summer progresses the heat warp will get worse. I suppose the blades purchased directly from a Chinese retailer would be mailed as purchased goods, not general merchandise bulk. That might get you better parts. Just a thought.