Allow traffic on one port from one IP address with iptables

I am using the following iptables rule to try allowing access to port 8080 from one IP address:

iptables -A INPUT -s 12.34.56.78 -p tcp -m tcp --dport 8080 -j ACCEPT

However, this rule isn't working. If I remove the -s 12.34.56.78 part, then it works, but it allows anyone access to port 8080 (not desired).

When I run iptables -L after applying the rule above, I get the following (which mystifies me - why won't it just display the actual IP in the source?):

root@wso-solr:/etc# iptables -L
Chain INPUT (policy ACCEPT)
target     prot opt source               destination         
ACCEPT     all  --  anywhere             anywhere            
ACCEPT     tcp  --  host-12-34-56-78.host.com  anywhere            tcp dpt:http-alt 
ACCEPT     tcp  --  anywhere             anywhere            tcp dpt:ssh 
ACCEPT     all  --  anywhere             anywhere            state RELATED,ESTABLISHED 
DROP       all  --  anywhere             anywhere            

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination

I'm wondering if this might be some sort of dns oddity that causes iptables to see the wrong IP address/DNS entry for my particular server (it returns the host-ip.host.com for source instead of the IP address...).