Yes, the bootloader rarely has a new version released. The only way to know if you need to update is to check the bootloader download (go to download.rockbox.org and browse to it) and see if the date is newer than the last time you updated.
Once RBUtil is the official install method, it's quite likely to include the option to update your bootloader (which will just replace it with the same version if yours isn't out of date, or may even detect and not update) for any players where a program can update the bootloader.