Not every single person has it but I would say it is present in at least 90% of the phones I have seen. My first iPhone 4S did it, my second one does it a little bit more audibly than the first. Every iPhone in the Apple store I tapped on the back near the camera made a rattle noise. Of course I had to put my ear up to it to hear because of the ambient noise but I would say it is "normal."
Once again, not everyone has it but the chances of your replacement having it (should you choose to do that) are probably 90% or higher. Eventually, you just have to cut your losses and realize that even when you might find one that doesn't rattle, what is the chance it will have a worse screen? Or a worse battery? The list goes on... Know when to call it quits and be happy with the phone.
Once again, not everyone has it but the chances of your replacement having it (should you choose to do that) are probably 90% or higher. Eventually, you just have to cut your losses and realize that even when you might find one that doesn't rattle, what is the chance it will have a worse screen? Or a worse battery? The list goes on... Know when to call it quits and be happy with the phone.