Thinking about exchanging mine, but not because of the sound, but just a lot of things adding up: vibrate rattle, echo during calls almost half the time (I can barely hear them having the volume down to 4, and that still apparently doesn't remove all the echo), pictures are coming out way to dark even with enough lighting (think someone else had this problem too and compared it with stores' stock), randomly getting warm (I'd have like no apps, but the power draw would be 400+ mA for no reason, signal strength doesn't seem to be a factor with this), and then that subtle click. The phone is great, but things for me are just starting to add up.
Edit: forgot to address the actual question, lol. If you just have the click I wouldn't bother exchanging it. If your starting to have other problems, then you might want to consider it if the problems are getting in the way of enjoying your device. The last thing you want is to be out of the exchange period,and still get annoyed with the problem you have and everytime you look at your device you just get OCD frustrated with it. I think that's what merits an exchange.