Hello Saul,
There were several bug fixes in DSpace 6.3 and 6.4 related to removing embargoed, private, and withdrawn items from areas of DSpace like searches, sitemaps and the OAI-PMH feed. You would be much better off upgrading to a more recent version of DSpace like 8.0 or 7.6.1, but if that isn't an option right now I would highly recommend upgrading to at least 6.4 for the numerous bug and security fixes.
Nick