Ever changing hashes since 5.4

Hey all, Since FortiOS 5.4 we notice ever changing hashes for "set priv-pwd ENC" "set auth-pwd ENC" etc. (snmpv3) and also for "set password ENC" commands in the configuration. Why is that? This makes the revision control of the config files kind of useless since there are always changes that are detected. One method would be not to backup those parts of the config, but which would also mean losing those passwords. Any idea? Thanks, Marki