Mute button works intermittently

My BlackBerry 9000's mute button is starting to act up. Sometimes it takes like 8 clicks to unlock it, and sometimes it works first try. But I have to say 90% of time it takes more than 1 time, when it used to always be first try.

I found another thread on another site that documents other users with the exact some problem (Standby / Mute Button intermittently stopped working - BlackBerryForums.com : Your Number One BlackBerry Community)

This would definitely fall under warranty or not?

snverhallen