Orphan files in /var/spool/mqueue.in

[Plant, Dean]

I am curious if the orphan files that I have to clear out of
/var/spool/mqueue.in every so often is something that other people
experience or do I have a problem that should be investigated further.
These files build up at the rate of about 3-4 a day on each server which
deal with about 30,000 messages a day, I have the lock type set to posix
and I am using the standard sendmail 8.13 rpm's from CentOS 4 with
MailScanner v4.52.2

Thanks

Dean