I suppose that your podcast is the Gamebites >> De gamepodcast in snackformaat. podcast, right?
I looked into the XML code of the feed of this blog and I could see that some of the posts have a
<pubdate> of the 2nd November although the episode title suggests that they older and that the order of the episodes should be different.
iTunes and probably all other podcast clients take this
<pubdate> information to recognise new episodes and to order the episode default.
I have also checked the default behaviour of WP + podPress again and I'm absolutely sure that the default behaviour is to leave the
<pubdate> as it as and to change only post content and informations like the categories.
That is why I think that Feedburner probably modifies this meta tag when it discovers updates of the content or other meta information like a new category.
I'm no Feedburner expert but maybe the features like the PingShot are responsible for this behaviour. But I'm not sure about this particular feature of Feedburner.