[CentOS] ssh reverse DNS failure

I use dyndns's (free) service to access a remote machine with a dynamic IP address. The machine is running under CentOS-6.0.

I can ssh into the address given me by dyndns (*.homelinux.com), but when I do this I get the warning "reverse mapping checking getaddrinfo for" * "failed - POSSIBLE BREAK-IN ATTEMPT!"

This doesn't really matter, as I normally use OpenVPN for accessing this site - the dyndns method is a safety precaution in case openvpn doesn't work.

But I'm wondering if it is possible to stop the warning? I've tried various recipes google gave me, eg adding "UseDNS no" to /etc/ssh/sshd_config on the remote machine (and re-starting sshd), but none of them has worked,