We are using a staging environment and courier to push changes to production.  Until 2 weeks ago, we had only two web servers.  We have recently added 2 more.  I have followed the setup instructions for setting up a NAS load balanced site, including setting up the APP_Data/TEMP virtual directory local on each web server.  The problem we are facing is that when a change is pushed from courier to the production environment, the changes are only applied to the first two web servers.  The umbraco.config file in the TEMP virtual directory on web servers 3 & 4 are not getting updated.  What I have had to do is manually copy the contents of the TEMP folder for the cache to 3/4 upon push to production and restart the site for it to pick up the new changes.

I am looking for any guidance if anyone has experienced this before.  The NAS is being serviced from a Windows cluster separate than any of the web servers.

umbraco v 4.7.2 (Assembly version: 1.0.4500.21031)