Keep messages forever notification on my iPhone

hi I just updated my I phone to the newest update. All was running smoothly but I had a concern about a notification I received. When I went onto messages on my Mac and iPhone it came up with a notification with your messages have been added to keep forever because a device has been added to messages on I cloud. There is no sign of malicious activity. I'm wondering if I should be concerned about someone hacking my account or if this is just my device not registering that my Mac and I pad are a part of my I cloud?

[Re-Titled By Moderator]