I noticed in two different phones(with two different chargers), that when charging using the enclosed charger, the touchscreen sensitivity gets all jumpy. You can try to recreate this by swiping down the notification bar halfway and holding it there. You'll notice the bar moving up and down. This problem also causes a lot of mistyped words when using Swype. If I disconnect the phone, or switch to my LG charger, the issue goes away.