In the buglist thread, someone pointed out the screen twitching under your finger.
But also only when you're not touching the battery cover or metal bezel around the screen.
You can test it by holding an icon (or the notification pull down bar)
under your finger while the phone is laying down on a table and plugged in.
It will move around a lot under your finger. But as soon as you touch the bezel with your
other hand it stops moving. It has nothing to do with being in a horizontal
position, because I've tested it while vertical too.