I am posting this to the forum at the request of Doug MacEachern, after an offline conversation about this issue...
I recently spent some time helping a colleague debug a memory leak, and tracked it down to sigar_rpc_ping() in sigar_util.c. I searched on http://jira.hyperic.com/browse/SIGAR and didn't see an open bug for this. I also checked the source code for version 1.6, and the issue appears to exist there (we were running version 1.5).
To be specific, sigar_rpc_ping() in hyperic-sigar-1.6.0-src/src/sigar_util.c calls clntudp_create() or clnttcp_create() and eventually executes: