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 callBut i'm not keen on going through multiple ipads if they all suffer from left-side yellownitis ;-)