An iPod doesn't count as one of the 5 authorizations, which only counts computers. If you're concerned about someone transferring your purchases or if its an iPod touch which has access to the iTunes Wi-Fi Store, you should probably just change your AppleID password at myinfo.apple.com. Signing in with your existing AppleID and then going to the AppleID section on the left will allow you to make changes to the password.
