It seems like people here, and Apple genius, don't know that minor manufacturing defects are always present in batch runs like this, and that your iPad could be from a bad batch. I had an engineer that specializes in this kind of engineering explain it to me.
Apple often finds these defects and has them corrected each and every month or so, maybe daily near launch week, based on previous returns. It's not to say that many came out defective, it could be only 1,000-5,000 out of a 1,000,000,000, but either way
1. They exist. So you could have one. It's likely
2. When Apple finds out, they tend to correct it for the next batch run
If you showed us a picture of a Microsoft Surface, you would be supported here. But because it's an Apple product, you're supposedly bending it with you buttocks. Apple doesn't manufacture these. It's the same suppliers that make Surface Books and other computing devices. Machined manufacturing still creates defects per million.
OP: if it bugs you, go to another Apple Store and ask for a replacement. Be polite, but be firm. Explain how much you paid, and what you expect.
PS: this is why a lot of informed people wait a few months after launch, because they know Apple improves the revisions after returns inform them of slight errors in the manufacturing.