When, how and if the mirrors sync up is up to them. So in the case where they haven't synced recently, it might be prudent to not show them in the list until they do.
Just info for those interested:
If an ISO is to be modified, i.e. a new ISO created during a quarterly cycle, the new ISO should have a new version number. For example, if I create PCLinuxOS-LXDE-2011-3 and then due to some need, must do another ISO a month later, it would be ~2011-4. If the change is within the same month, it can be versioned as ~2011-3.1.