Automatically delete old podcast files.

[mbozzer]

I'm a new user and would like some clarification.  I understand that podcast files are supposed to get deleted automatically.  I'm not synching any devices, just listening on desktop application.  
I have the podcast library set to keep all unplayed episodes.

When do the podcast files actually get deleted from the computer?  There are podcast files in the Windows folder that have been listened to over a month ago.
Is there another setting?  A process that I need to run?

Also, I don't ever close the application, just pause the currently playing podcast.

Thank you.

[ma_t14]

After a quick test, they seem to get deleted on MB's startup