I found the source of the activation error and am looking for the most appropriate place to post about it. (This is my first plugin bug find!)
Inside the pagemeta folder, in the file index.php lines 29-30 show the following:
register_activation_hook(__FILE__, array(&$pageMeta, 'activate'));
register_deactivation_hook(__FILE__, array(&$pageMeta, 'deactivate'));
Change both of the ‘$pageMeta’ variables to ‘$this’:
register_activation_hook(__FILE__, array(&$this, 'activate'));
register_deactivation_hook(__FILE__, array(&$this, 'deactivate'));
After this change I no longer get the warning message on activation.