Having used my Touchpad only a few times, as compared to everyday, I have noticed a crack on the left speaker. Now going back to day one I did notice that the glass was raised up a few mms and I could catch my finger on it.
After fearing that this is somehow damage I caused, I started looking around the web to see if anyone else has come across this problem before. A bit to my surprise there are a few long threads on the main Palm Forum about this issue. Phew... I'm not alone.
I'm currently setting up a repair case with the Palm/HP/WebOS team to get my TouchPad repaired - hoping that I don't get a replacement.
I guess what I will need to do is restore it to factory settings incase they don't like the fact I have loaded CyanogenMod's Android port onto it. :-) But I must say that the Android install is pretty slick, and doesn't overwrite the default WebOS install.
Ref http://forums.precentral.net/hp-touchpad/288235-touchpad-case-cracked-sp... amongst others
