Another persistent niggle on our CTDB-based cluster is that occasionally we'll see a few files, or infrequently directories, that have a mask of "rwx" get changed to "r-x" or even "---". This has the effect of locking out additional groups or users in the POSIX ACL.
Most often this seems to happen when we have to stop CTDB on one or more of the servers, but it does seem to have happened on other occasions, if rarely.
This is almost always on Excel and Word documents that are opened from Windows XP/7 clients.
CTDB does not affect any files on the shared file system.
Do you have exact steps to reproduce this problem?