Played podcasts on iPod not syncing properly

I am having a problem with the syncing feature of my iPod Nano. I use it exclusively for podcasts. Until a couple days ago, whenever I listened to a podcast, even a few seconds of it, the iPod would remove the blue dot and consider it played. Then when I synced to my computer, all played pocasts were removed from my iPod and all new ones loaded. This was working great for me.

Suddenly with my last couple syncs, no podcasts have been removed from the iPod at all; the blue dot has been restored to the ones I listened to, so they are marked as unplyaed; AND the freshly-downloaded podcasts in iTuneshave been added to the iPod as well.

My sync settings are "Sync all new episodes of all podcasts."

I have tried right-clicking on each main podcast name in iTunes and choosing Allow Auto Delete, then closing iTunes and opening it again. No dice. I have tried starting a podcast on the iPod, then scrolling it right to the end, then syncing. Still no dice.

I can't think of anything I did which would have caused this bug to appear. I don't think any iTunes updates have come in recently.

Help!