Have you recently noticed the following error message in /var/log/secure with RHEL/CentOS 6?
PAM unable to dlopen(/lib64/security/pam_fprintd.so): /lib64/security/pam_fprintd.so: cannot open shared object file: No such file or directory
PAM adding faulty module: /lib64/security/pam_fprintd.so
There is several bug reports regarding this. I think PAM is trying to load an inexistant module. You should be concerned only if you have a fingerprint module. If so, just install it as followed :
yum install fprintd-pam
Otherwise, just disable it :
authconfig --disablefingerprint --update