Possibly due to the current Google Cloud outage. <a href="https://status.cloud.google.com/incident/compute/19008" rel="nofollow">https://status.cloud.google.com/incident/compute/19008</a>
Exactly for this, I have built <a href="https://IncidentOK.com" rel="nofollow">https://IncidentOK.com</a> which sends alert over email/slack to user if any third party services like this reports an outage or incident.