I had some time to waste trying things to check out this nagging issue on my 32GB iPod Touch 5. It takes an extra 40 seconds to restart my device because of this issue. The issue occurs on: iOS 8.0, 8.01, 8.02 and 8.1 beta.
First I made a backup to iTunes and copied the backup file.
These steps failed to correct the problem:
Set airplane mode, restart.
Logging out of iCloud, restart.
Logging out of iTunes, restart.
Reset network settings.
Reset all settings.
This “fixed” it:
Erase all content and settings.
This “broke” it again:
Restore backup (from iTunes)
So it has something to do with my apps and/or data installed on the iOS 8 device. On iOS 7, this issue did not exist.