I think that this has been resolved in M5 or in the latest snapshot. Try them and then write here if it will still occur especially if it will be present in the latest snapshot.
it is a known bug https://issues.jboss.org/browse/RF-8984 which is not caused by RichFaces but by Mojarra http://java.net/jira/browse/JAVASERVERFACES-1646. I haven't seen this bug for long time. Could you please provide more information about JSF version and application server you are using?
There is a simple workaround for it. Just add following to the web.xml: