The update functionality didn't work in the beta in RC versions hence the reason why it didn't tell you to update. I certainly advise you to uninstall and update because the GA version fixes lots of things and we don't support the beta or RC versions anymore.
BUT, before you do, it is important to know a few things:
1. You will need to start over again. We made significant changes between RC and GA. Uninstall the RC (control panel, add/remove programs) and re-install the GA version. That means you need to recreate your backup job and the recovery ISO? There are no worries about the USB hard drive registration though. When creating the job again, just point it to that HDD and it will be used again.
2. It will become a whole new backup chain. As said, the changes are too big to continue to use the old chain.
3. You won't be able to recover from your old backups anymore. If you still think that will be necessary, I advise you to keep the backups (until the X days are over), keep the installer for the RC somewhere safe, and if necessary, install RC on a VM (then you can use that one to recover whatever you want from the old backups)