I don't know if this was covered, but I think the lock screen is more discriminating in how it registers an unlock. I think that they changed it so that your finger has to travel in a more "left to right" motion, otherwise, the screen just snaps back into place. I don't know if that makes sense, but basically before, you could drag your finger nearly strait up and slightly to the right and it would still unlock. Not that anyone ever unlocks their phone that way, but I bet that's how it gets unlocked accidentally. Now you need to be within a certain cone shaped area, and if the path of your finger gets oddly interrupted (like if you drag your finger strait up halfway into the slide), the unlock will fail. Has anybody else noticed this?