The latest release was added to the patches section for customers of the 1.3.x Professional Edition versions, but I've had issues in the past with these patches not being available for some customers.  I think it has to do with how I version metaPost through the Snowcovered interface.  I'll look your email address up and send you a copy of the latest release.  You may also want to create a ticket with Snowcovered to let them know that even though each of the 1.3.x Professional Edition versions have been added to the latest metaPost patch you don't have access to it.

Thanks,

Don