I recently noticed that my Gmail From Sorter Greasemonkey script stopped working, but as usual “out of sight, out of mind”; having sent the email, I promptly forgot about the problem. I was reminded again tonight when Robert emailed me about the issue, so I set about correcting it.
A few hours later, and GFS 1.4 resolves the problem. You can download it from the Gmail From Sorter Userscripts.org page, or you can wait for the auto-updater to kick in, which should take a week at most. Thanks Robert!