First iPhone 6 128GB Gold I opened at the store had pretty clear spotlighting in the top edge. Like edge bleed of the backlight, little dark triangles about half a centimeter apart across the top. I'm an art director and insanely anal though, so I'm sure not everyone would notice/care.
The employee looked at some of the other display 6 models and they all had the issue, but fainter. We opened up a second 6 and it too had the problem, only slightly less. Shrugged and took it home, I've noticed it has diminished the more I've used it.
Luckily no dead pixels or dust issues. Went back to a different Apple Store today to exchange a case, and noticed the top edge very subtle dark issue on every demo phone.
The 6 Pluses I saw didn't seem to have any backlight issue.
It's so faint now I'm pretty sure it's in the "imagination" category that I will forget about it soon enough.
I have this same issue. It's pretty minor though and I didn't notice it until my second day of use when reading in the Kindle app. Good to hear that it has diminished, but that also could be just because you're getting used to it.
After my experience with my 4s, I've decided not to return it for this issue. There are no dead pixels, the screen is bright and overall uniform, and there are no issues with any parts or cosmetic problems. My first 4s had the spotlight issue on the top as well, and I exchanged it at the Apple store a few days after I got it because of this. That was a mistake, because it took me about three more returns over the following few weeks to get a replacement that didn't have serious problems. On one replacement, my WiFi stopped working after a few days. I'm just going to stick with my current 6 and not worry about it. I've also realized since then that there are a lot more important things in life to worry about than a small difference in lighting in a very small top part of my smartphone.
On a different topic, one thing I did notice is software related. I don't like to show all of my iTunes music on my phone, so if I want to download something I purchased on another device I just open the iTunes app, go More -> Purchased -> Recent Purchases.
All my songs show fine, but as soon as I download one it takes me back to the More page, and the Purchased icon/word has now disappeared. The arrow on the far right is still there, though. If I click this blank space it'll take me back to purchases, where I can download another song. But I have to do this one by one, before I could just tap the cloud button and download as many songs as I want.
I'm thinking this is a software issue that'll hopefully get resolved soon. Anyone else have this?