@dibbern2: Ditto. I think the system might be broken, too.
4-5 days ago I had the alert again, due to the Australian version of Google. So I added it to the authorized sites list.
But the alert is still there, almost a week later. I keep checking but no new 'unauthorised' sites are appearing. So I'm wondering whether the system's broken since it's showing a continuous warning without having any unauthorised sites.