Timed Out

Hi, in log file I have this error with SA-3.2.5 and MySQL-5.0.77 (with 
amavisd-new, postfix, maia):

Jul 23 11:03:35 mail amavis[6329]: (06329-02-2) SA TIMED OUT, backtrace: at 
/usr/lib/perl5/vendor_perl/5.10.0/Mail/SpamAssassin/BayesStore/MySQL.pm line 
492\n\teval {...} called at 
/usr/lib/perl5/vendor_perl/5.10.0/Mail/SpamAssassin/BayesStore/MySQL.pm line 
492\n\tMail::SpamAssassin::BayesStore::MySQL::tok_touch_all('Mail::SpamAssassin::BayesStore::MySQL=HASH(0xb8bfcec)', 
'ARRAY(0xb19ce24)', 1248337394) called at 
/usr/lib/perl5/vendor_perl/5.10.0/Mail/SpamAssassin/Bayes.pm line 
1284\n\tMail::SpamAssassin::Bayes::scan('Mail::SpamAssassin::Bayes=HASH(0xb6a92bc)', 
'Mail::SpamAssassin::PerMsgStatus=HASH(0xcfda70c)', 
'Mail::SpamAssassin::Message=HASH(0xd1bb9dc)') called at 
/usr/lib/perl5/vendor_perl/5.10.0/Mail/SpamAssassin/Plugin/Bayes.pm line 
50\n\tMail::SpamAssassin::Plugin::Bayes::check_bayes('Mail::SpamAssassin::Plugin::Bayes=HASH(0xb7647cc)', 
'Mail::SpamAssassin::PerMsgStatus=HASH(0xcfda70c)', 'ARRAY(0xba621dc)', 
0.99, 1.00) called at (ev...

..this error is present  occasionally but several times in a day.
This error is caused by SA or MySQL ?
Thanks.

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  Salvatore.