After upgrading to WordPress 3.9.1 I found that this plug-in stopped working. One of the issues I found is not necessarily with the plug-in itself but with the WordPres Cron jobs not executing. Some of our sites do not actually receive enough direct traffic to trigger the cron job when the home page is accessed, as we use JSON Feeds to update another site with published posts.
The work-around I found was to force a scheduled load of the home page by using a system CRON job (or Windows Task if using Windows) to force the WP Cron job to kick in.
This appears to have resolved our problem of posts not expiring as scheduled.
