Please note this (as the same questions come up again and again):
1) .55 does NOT solve the touchscreen problem.
2) It seems, many Z2 don't show any creaking tendencies right after delivery, BUT after using the tablet for some days.
3) My LTE Z2 had NO touchscreen and NO creaking issues right after unboxing, but came up with that two problems after two days of use.
4) Many Z2 have a warped, bent chassis, putting the device under constant physical tension. Peek along the sides of the Z2, and you'll see.
This might be the reason for "late" creaking and touchscreen issues. But this is just a guess.
I ordered another LTE Z2 yesterday, should hit the ground tomorrow. Let's see if it's a banana or not.
I'll try to open a separate thread for collecting information about bent devices, touchscreen and creaking issues. Maybe there's a connection.