I've been using the django syndication-feed framework for about 9 month now and i keep having the same problem. Every now and then, for no apparent reason my rss reader (google reader) is flooded with all the old entries, which I already received when they were up to date. I failed to find a connection between these happenings, it's not always the same feed (I'm using different feeds for different kinds of postings) and it has nothing to do with rebooting the server.
Does anyone have a clue on why this happens?