Your log doesn't show any errors but, since we had a new update today, it's probably worthless investigating about it now.
If it happens again, pay attention if the Couatl icon is still active in the Tray bar but, do not just look at the icon but, hover with the mouse over it, because Windows doesn't always refresh the icon automatically so, maybe it's gone, but you wouldn't know unless you hover with the mouse over it.