The time in the widget is correct, in the bar is wrong. I have experienced this before with my previous Xperia Z. But now with the Z5 as well. Good to know, I gave my Phone a factor reset a couple of weeks ago and it's been updated. Not rooted.
Sure, the problem is that when this happens and I reboot the phone, the problem is solved. I'm just curious about how it can happen in the first place. And how I can prevent it from happening.