I often found my phone's desktop all messed up after I take it out of my pocket. So also here my phone is unlocking itself automatically. I really don't know why this is.

My guess is a combination of (1) the "Lock screen automatically" setting in the display-menu isn't working (known bug?), eg I can wait as long as I want, but my phone does not lock after the background time-out and (2) the glitch mentioned in the post above. I can confirm what is written there. It takes some time to 'learn' how to do it, but must most of the time I can unlock the phone when I keep pressing the power button in the same frequency as to lock it.

Are the more reports of these two locking problems?