I've gotten emails a week in advance and again a day in advance when an instance needed maintenance that would result in a 10 second network reset, so it'd really surprise me if Amazon completely retired an instance with no notification. This person must have missed the email or it got spammed.
One or more of your Amazon EC2 instances have been scheduled for
maintenance. The maintenance will result in a reset of the network
connection for your instance(s). The network reset will cause all
current connections to your instance(s) to be dropped. The network
reset will take less than 1 second to complete. Once complete your
instance(s) network connectivity will be restored. The instance(s)
will have their network connections reset during the time window
listed below.
You can avoid having your network connection reset at the specified
time by rebooting your instance(s) prior to the maintenance window. To
manage an instance reboot yourself you can issue an EC2 instance
reboot command. This can be done easily from the AWS Management
Console at http://console.aws.amazon.com by first selecting your
instance and then choosing ‘Reboot’ from the ‘Instance Actions’ drop
down box.
