This isn't the kind of email I like to see when I wake up:

Our backend monitoring system has detected an error on the host where your Linode resides which could lead to a failure condition. In order to protect your Linode, we have scheduled an emergency migration to a different host which will commence shortly. Please note that there is currently no issue with your Linode - this is a proactive measure we are taking to avoid an issue in the future.

We apologize for any inconvenience this may cause. Should you have any questions or concerns, please do not hesitate to reply to this ticket.

The server rebooted and my sites didn't come back up, so there was some downtime. Sorry about that.