Creating default object from empty value boxes_box.inc:28, PHP 5.4

Hello mantainers,

I'm getting the error message described on title when running cron via drush and the following error message on logs:

Warning: Creating default object from empty value in boxes_box::load() (line 28 of /sites/all/modules/boxes/plugins/boxes_box.inc).

The code is as follows:

  public static function load($delta, $reset = FALSE) {
    if (!isset(self::$boxes[$delta]) || $reset) {
      ctools_include('export');
      $box = ctools_export_load_object('box', 'names', array($delta));
      if (!empty($box) && $values = array_pop($box)) {
        self::$boxes[$delta] = self::factory($values->plugin_key, $values);
        self::$boxes[$delta]->new = FALSE; // Line 28
      }
    }
    return isset(self::$boxes[$delta]) && get_class(self::$boxes[$delta]) != 'stdClass' ? self::$boxes[$delta] : NULL;
  }

I see that this error was supposedly fixed as described on https://drupal.org/node/1279752. Checked the code and its up to date on dev, which was updated on April 10th, 2013.

Can you give me a lead on what's the problem and/or how to fix it? Thank you for your time.