I've got this problem on my iPhone 5s Space Gray. The home button seems to be making a loud clicking noise on the way up. Compared it with two other 5s phones: one other Space Gray - the clicking noise is not as loud and more uniform on the way down and up - and another Silver - also has a fairly loud clicking noise, but on the way down, not up. Accordingly, it appears that all 5s phones are different, not uniform. The loud clicking noise on the way up is annoying the living hell out of me. It's a Sprint phone; I also visited a Sprint store, and the staff memeber there was not able to tell the difference between my 5s Space Gray and another 5s he had on display. As a result, I have a tendency to think this is more likely a flaw/oversight in the phone design, not a "normal" feature of 5s like some have commented earlier on this forum.
Has anyone had a positive experience bringing their 5s to an Apple store and exchanging it to get rid of the issue for good? Or do they all click? I'm starting to really consider a visit to the Apple store.