We have a minor hosting change to make (change how an instance of memcached is managed) that will lose all of the current release editor sessions. We will make this change tomorrow, Thursday at 20:00 UTC. During this time, any release editor session that is active will break and you will lose your changes in the release editor. To prevent this from impacting you, make sure to submit any changes before 20:00 UTC and wait for us to post another entry saying that the change is complete.
The rest of the site will be unaffected by this change.