Drupal 7: Is hook_update_N() called when a module is updated between minor versions?
hook_update_N is only invoked when:


The update process is running (via /update.php, drush, etc).
The current schema version for the module is less than the update hook's schema version (The N in hook_update_N).


No updates are run when you visit the modules admin page, the process will always be invoked by an administrator (or perhaps an automated task, but never silently/automatically by Drupal itself).

As an aside (in case it comes to bite you at some point), no update hooks are invoked when installing a module, only for already-installed modules during the update process. The update hooks are only for getting older installations up to speed with what the current release offers upon installation anyway.

As another aside, your schema numbering looks a bit suspect if you want to stay within common practice; have a read through the hook_update_N docs for more info, but your numbering should probably be in the 7100s at this point.