i have the same issue, except mine is only on the left hand side of the pad.
the right side if you tap to click is firm and no audible sound whatsoever.
on the left, it makes a clicky noise. Very annoying!!!
it is almost like there is double stick tape underneath the pad and one side has lost its adhesive property. if i push it down with a little force, and let go it sounds normal for a few min. then right back to clicky, clicky.
weird...
i am very upset too. i finally found one that is "cosmetically" up to my standards and then this. i am reluctant to have it repaired because everytime i have had the apple store fix something and a computer it has come back with scratches and blemishes that where not there when i sent it out.
it's been said before, when you by a new apple anything, you are entering
the "Apple QC Lottery" sometimes it's your lucky day, but most of the time all you get is a loser.