1. Sometimes when I receive a call the phone responds really slow. I mean sometime screen turns itself on really late (after 2-3 seconds) or it waits on lock-screen for a couple of seconds and then draw the phone application really slowly (it first displays without the number, the displays the calling number than displays the contact picture).
2. Another thing (most likely related to the same issue) sometimes when I turn my phone on from a stand-by, it fails to display lock screen a few seconds (sometime it take 5-6 seconds)
3. And sometimes when I turn my phone on from a stand-by, it doesn't display the lock screen at all. But when I press on power button again, if briefly (maybe for a fourth of a second) displays the lock-screen than goes to stand-by mode again.
4. When I plug my phone to computer, it displays "USB plugged in" screen and there I can turn usb storage mode on, even though my phone supposed to be lock-pattern protected it skips the lock screen for usb connect dialog. (after I open usb and press home or back buttons, it returns to lock screen but I can actually turn usb storage mode on and access my files without entering the lock pattern.