Your plugin is really cool and I am using it on several sites.I think one more addition would make it more perfect.
I run some offers on my site and change them normal category to "expired " category through this plugin.But sometimes visitor directly come to post through Google and they don't realize it is an expired post or they get confused.
I would suggest you to add one more word (EXPIRED) in heading when it changed from normal category to expired category.For example, heading in normal post "Get Free plugin" after moving this post to expired category post heading should be like "Get Free plugin-EXPIRED"
You can check the live example here
Thank you for sharing such a great Plugin.