Notification number in toolbar

When I click on the notification icon in the toolbar on my profile page, after I close the window the number is still visible. If I click back on the icon, it shows that there are no more notifications. The number of notifications is still there on the icon. Should the notification number still be there is there are no more notifications to be read? If I click on the Mark all as Read link in the notification window the number is removed.

See video: http://screencast.com/t/ktr81MBF3I