1) When the phone is locked and I receive a call, sometimes when I swipe up to answer, the lock screen would just bounce up and down (like what happens when you tap your lock screen). I would need to press the lock button twice (Once to turn off the screen and then to turn it on again) before I can swipe up as normal.

Phone was bought with WP8, later updated to 8.1. The problem persisted in both versions, and a friend using a different Lumia also has the same problem.


2) When the phone is locked and I press the lock button, the screen will light up for a second before turning off by itself. I would then need to press the lock button 1-2 times to turn on the screen again. Noticed this only after WP 8.1


Anybody knows what's causing these?