dovecot - Oct 2007 - v1.1.beta2 - maildir quota calculation problem

I have a problem with the maildir quota plugin. Any imap operations cause 
the plugin to recalculate the mailbox size and put the new value in the 
second line of the maildirsize file, while the third line always contains 
the size of the latest operation. So the resulting sum is incorrect. 

Moreover, quota-warning is not working either.
Have anybody else met such problem?

mail# ./dovecot -n
# 1.1.beta2: /usr/local/etc/dovecot.conf
...
mail_plugins(default): quota mail_log
mail_plugins(imap): quota mail_log
mail_plugins(pop3): quota
mail_plugin_dir(default): /usr/local/lib/dovecot/imap
mail_plugin_dir(imap): /usr/local/lib/dovecot/imap
mail_plugin_dir(pop3): /usr/local/lib/dovecot/pop3
...
plugin:
  quota: maildir
  quota_rule: *:storage=10240
  quota_warning: storage=75%% /usr/local/etc/quota-warning.sh 75