Okay so the podcasts are working in iTunes now. The issue was with W3 Total Cache plugin and what fixed it was to edit this setting:
Never cache the following pages: /podcast-download/.+
One more question before I resolve this ticket. It looks like the podcast episode description in iTunes is pulled from the WordPress content. On our website we use the WP content to display more information then we would like to include for the iTunes description. Is there a way to send a custom/shorter description to iTunes for use?