It must check on a schedule, that would explain why some people aren't getting update notifications right away. It doesn't "push" updates, it just notifies you that there are updates, and you have to tell it to pull the update.
THANKFULLY it just notifies you of updates. Just think of what happens when you update an app your using at the same time or maybe the new version does something you don't like??? It does the update checks in the same way the OS update app does it.
Try diplomacy first. You can always conquer them later...