InfoPath Dev

We have a form that is published to a SharePoint Document Library. Some conditional formatting changes were implemented to the form and published without the "Automatically upgrade existing forms" being checked. However we needed the old/existing forms to be upgraded to show the new changes, so we re-published the form with the "Automatically upgrade the existing forms" button selected. All but nine (of several hundred) of the forms in the library were upgraded. These nine forms seem to be "locked" and we can't seem to figure out why they won't upgrade while all the others are working correctly. Any ideas?

After looking through the version history for each of the forms that wouldn't upgrade, we determined that the form had upgraded, but then someone with an old form opened the file and saved it overwriting the newer version. We don't understand why the form wasn't replaced with the newest version the next time someone else opened it, but we were able to fix the problem by going back to a previous <correct> version of the form. =)