[Dovecot] corrupted index?

[Gary Funck]

We're seeing the following sporadically in
the log file (single line broken into separate
lines for readability):

Corrupted index cache file 
/home/user/mail/.index/.imap/INBOX/dovecot.index.cache:
invalid record size

We're running dovecot-1.0.7-2.fc8.  The imap directory
is in the user's NFS-mounted /home directory, but
doveot is running on the same host as the
/home filesystem.  There's plenty of disk space and
no other significant system problems.  The mail
index directory we rm'd a week/so ago, so doveoct
has had the opportunity to rebuild it.

Any ideas on what might be causing this?  Is this
issue anything to worry about?

thanks.