Double check to make sure podcasts are configured to sync to your device from under the iPod's Podcast configuration tab.
To access the Podcasts tab for your iPod, plug your iPod in and click on it from under the Devices section in the left hand pane of iTunes. This will bring you to the Summary tab. Along the top you should see a Podcasts tab, so go ahead and click on it. Here you can configure how and what podcasts sync to your iPod.
If you do make any changes to do this tab, make sure to hit the Apply button in the lower right hand corner to apply the update changes to your device.
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