IPhone :: On/Off And Volume Buttons Making Loud Noise When Pressed?

I recently purchased an iPhone 4S brand new and sealed and it's been about a month now and the on/off button and volume buttons seem to get stuck when being pressed. I have to apply more pressure than generally required to get them to function correctly. And when I do that, I hear this loud clicking noise as if the button was not making the right contact with the insides and happens to sit in place after the pressure is applied. It feels like I'm cracking the inside of the phone every time I press them so kind of worried about it.

Another thing I've noticed it when I press the Up volume button, the volume goes up and then back down sometimes in an instance, as if the button seems to be pressing the down volume button aswell from beneath it. The rest of the phone is fine. Is this a common issue and will I be able to get this fixed under my warranty as it is covered til next year?

Info:
iPhone 4S, iOS 5.0.1