[Dovecot] Question about log entry?

[Knute Johnson]

dovecot: POP3(knute): mbox sync: Expunged message reappeared in
    mailbox /var/mail/knute (UID 585 < 379664, seq=2, idx_msgs=0): 1
    Time(s) dovecot: POP3(knute): mbox sync: UID inserted in the 
middle of
    mailbox /var/mail/knute (379664 > 585, seq=2, idx_msgs=1): 1 
Time(s)

I've been getting these lately.  Any idea what causes them?  Should I 
worry about it?

Thanks,

-- 

Knute Johnson
Molon Labe...