/var/log/messages flooded with 'sql plugin' notices from postfix

Hi,

I am using postfix 2.1.4 with mysql lookups and SASL2, which also uses
mysql. All software was compiled from ports. I am getting a lot of the
following messages in my /var/log/messages :

Sep 19 22:59:18 mail postfix/smtpd[21751]: sql plugin: no result found
Sep 19 22:59:18 mail postfix/smtpd[21751]: sql plugin: no result found
Sep 19 22:59:33 mail postfix/smtpd[18395]: sql plugin: no result found

This is basically when a user specifys an invalid login. These messages
are very frequent and are polluting my messages log. Is there any way to
have postfix disable these notices?

P.S. I have tried the postfix mailing list, but they redirected me here :P

Thanks.