[rdiff-backup-users] UpdateError - what does this mean?

[Neal Becker]

Starting increment operation /home/nbecker
to /var/backups/rdiff-backups/nbecker1/home/nbecker
UpdateError .kde/share/apps/knode/nntp.1/gmane.comp.web.openid.general.dynamic
Updated mirror temp
file 
/var/backups/rdiff-backups/nbecker1/home/nbecker/.kde/share/apps/knode/nntp.1/rdiff-backup.tmp.1018
does not match source
UpdateError .kde/share/apps/knode/nntp.1/gmane.comp.web.openid.general.grpinfo
Updated mirror temp
file 
/var/backups/rdiff-backups/nbecker1/home/nbecker/.kde/share/apps/knode/nntp.1/rdiff-backup.tmp.1019
does not match source
UpdateError .kde/share/apps/knode/nntp.1/gmane.comp.web.openid.general.static
Updated mirror temp
file 
/var/backups/rdiff-backups/nbecker1/home/nbecker/.kde/share/apps/knode/nntp.1/rdiff-backup.tmp.1020
does not match source

I'm guessing this is because files changed during backup?  But does this
mean my backup failed, or is it just a warning?

If it just a warning, the message should be changed to be less scary.