Syslog-ng (when compiled with USE=selinux) has rules to direct audit log info from kmsg, to /var/log/audit.log. This file, however, is labelled in a way that doesn't allow syslog-ng to access it. So either syslog-ng should be able to access it, or the rules should be removed from its default config file.
fixed in selinux-base-policy-20061015. you'll have to restorecon the file after updating.