Yes because I ordered via the online Apple Store. Unless I'm mistaken, I couldn't have returned it to any "physical" Apple Store.You called them instead of going to a store?
If you notice the unevenness and it distracts you (like mine does to me), exchange it.I got one at a store but the left side being more slightly darker/yellower kind of gets to me. I'm very sensitive to uneven lighting/color so it's kind of a bummer. my ipad 1 doesn't have this issue.
There's a definite chance that a replacement would come from the earliest batches so it may have this problem as well (or worse). Your call 😉.But i'm not keen on going through multiple ipads if they all suffer from left-side yellownitis ;-)