Was my Lightsail instance replaced?

I have a Bitnami Wordpress Lightsail instance that's been deployed for roughly a year. I've snapshotted it and replaced it in the past, however, something strange happened. I received a notification that the website was down at 13:10 and then notified that it was up at 13:38 UTC. I had an active ssh session at the time that was terminated. When reconnecting to the site via SSH, I got the notice that the host SSH key had changed. I was able to connect by clearing the key. The last logged in user prior to me was the user "reboot". The system was not manually rebooted. Looking at the CPU metrics, there is a gap in telemetry during this time period. The last log entry in /var/log/syslog prior to the system booting is this ^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@

The same line is in the apache access log as well.

Any thoughts on what's happening here?