Just curious, but why did you take it off?
the trackpad lost responsivness. sometimes it'd work fine. other times i would move one finger numerous times and get no response at all. since i've taken it off it's been fine.
thus, i highly recommend the palm guard, i do not recommend putting the trackpad cover on at all.
Trackpad wear?
no. the machine is only 3 months old. the difference was the trackpad is not as sensitive if you have something covering it (e.g. moshi palmguard trackpad protector)