[Gangrel]

After having my new pixel 2 XL for less than 24 hours, I saw some banding and a blob on the side of the screen. I'll attach a photo if it works. I contacted a Google support which had me try a few things. But then they told me I should try the retailer first. I haven't had a chance to go back to the store yet. But now it seems the issue may have gone away. Has this happened to anybody else? The line and blob were pretty visible at first but now I can't really see them. I'll attach what they look like when I've first notice the problem.

Should I still try to get a new phone? Or was it something weird since it was brand new and that'll never see it again?

[TraderGary]

Your images appear to be a combination of reflections and application formatting. Are you seeing the same problems with all apps or just some apps?

[GSDer]

Did the band move up/down as you scrolled the screen contents?
Was that blob always attached to the band?
Were those artifacts always there regardless of what was on the screen?
Did it still appear after a reboot or in Safe mode?

[Gangrel]

Did the band move up/down as you scrolled the screen contents?
Was that blob always attached to the band?
Were those artifacts always there regardless of what was on the screen?
Did it still appear after a reboot or in Safe mode?

Yes, yes, yes, and yes, even after a factory reset.

[Gangrel]

Your images appear to be a combination of reflections and application formatting. Are you seeing the same problems with all apps or just some apps?

When the issue was there, it was in all apps.

[applejosh]

Is that notch on the side part of that anomaly? I'd still probably swap it out just to be safe if it's not too far away.

[Gangrel]

Is that notch on the side part of that anomaly? I'd still probably swap it out just to be safe if it's not too far away.

It was. But the band and the notch or blob has now disappeared, which is why I'm perplexed.

[applejosh]

It was. But the band and the notch or blob has now disappeared, which is why I'm perplexed.

Kind of sounds like a loose connection or something somewhere.

[GSDer]

Yes, yes, yes, and yes, even after a factory reset.

I can't explain why the problem went away but I'm not sure I'd trust the hardware. Since you're within the (usual) 14 day return window I'd suggest getting it replaced.
Of course, if you keep it and the problem does reappear, at least you have the Google warranty period to rely on.