I was going to post back that after a reboot there hasn't been any problems but it happened again this morning. When you scroll down it starts jumping around like crazy. I noticed as well while playing a game that it stops accepting touch inputs for a few seconds some times.
Also when it was doing this, while on the lock screen it was flickering and showing the home screen briefly (through the lock screen)
I'll try the screen test posted above and raise a case with support.
I noticed it in a settings menu, but it's anything you are scrolling down in.
Sorry I realise this has hijacked the original topic.
I love the phone though, I was worried that the case would feel like one of those cheap silicone cases you get but it feels great.