Well, When you put the redirect in at Feedburner, you should have put the /feed/podcast/ feed in there. iTunes updated with the redirect you put in feedburner for your podcast which was your main site feed.
Now, like I said, I would (if I were in that position) do a 301 from your main site feed to the podcast only feed. This will get iTunes to change to the Podcast Only feed. Once that is done, turn off the redirect. Write a blog post saying that if you are subscribed to the blog's main feed, you will need to resubscribe.
The iTunes new feed URL tag (I don't believe) goes in the main site feed.. Just the podcast only feed. So iTunes wouldn't know anything about it since it's looking at your main feed.
-Mike