My new Pixel XL has a faint rattle in the upper part of the phone. I was/am worried about this and can immediately send back and get a new one.

However I Google'd it and saw that one or two people said NFW, definitely exchange it, BUT I saw a few people, 2 Pixels and one Nexus 6P and they said that it is absolutely fine

They told me to tap it and hear the rattle...which I did

Then they said open the camera app....which I did. The sound was gone. They said it was the mechanical part of the lens

If I could get your opinion on this, on the Pixel or any other phone I'd be very grateful.