[Dovecot] bug? Maildir ... sync: UID inserted in the middle of mailbox

Version: 1.00alpha2

Error: imap(grin): Maildir /home/grin/Maildir sync: UID < next_uid (94 < 95, file = 1127311363.H977932P25148.gollum:2,)

   imap(grin): Maildir /home/grin/Maildir sync: UID inserted in

the middle of mailbox (95 > 94, file = 1127311363.H977932P25148.gollum:2,)

This error reappears frequently.

Doesn't go away by restarting dovecot, but does go away when I delete all index and cache and whatnot (and restart dovecot).

Appears in 10 minutes again...

Could be sylpheed-claws-whatever-alpha imap problem, but whatever the client does dovecot shouldn't be fall apart I believe.

Peter