Home button on iPhone 4 issues.

Hey, so I have a Black iPhone 4 16gb from Verizon.  I got it in the presale for existing Verizon and for the most part everything has been working great on it.  Anyway, lately (the past month or so) I've noticed that I've been having to press harder and harder on the home button to get it to function.

Just wondering if

a) has anyone had this problem

b) any fixes for it

c) I'm still under warranty...do you think apple could fix it or get me new one?