PHP Notice when a date starts with '('

Example:

    $feed = new SimplePie();
    $feed->set_feed_url(array('http://feeds.feedburner.com/surfline-rss-surf-news'));
    $feed->init();
    foreach ($feed->get_items() as $item) {
        $item->get_gmdate();
    }

Result:

    PHP Notice:  Uninitialized string offset: -1 in /simplepie/library/SimplePie/Parse/Date.php on line 723
    PHP Notice:  Uninitialized string offset: -1 in /simplepie/library/SimplePie/Parse/Date.php on line 723
    PHP Notice:  Uninitialized string offset: -1 in /simplepie/library/SimplePie/Parse/Date.php on line 723
    PHP Notice:  Uninitialized string offset: -1 in /simplepie/library/SimplePie/Parse/Date.php on line 723
    PHP Notice:  Uninitialized string offset: -1 in /simplepie/library/SimplePie/Parse/Date.php on line 723
    PHP Notice:  Uninitialized string offset: -1 in /simplepie/library/SimplePie/Parse/Date.php on line 723
    PHP Notice:  Uninitialized string offset: -1 in /simplepie/library/SimplePie/Parse/Date.php on line 723
    PHP Notice:  Uninitialized string offset: -1 in /simplepie/library/SimplePie/Parse/Date.php on line 723
    PHP Notice:  Uninitialized string offset: -1 in /simplepie/library/SimplePie/Parse/Date.php on line 723
    PHP Notice:  Uninitialized string offset: -1 in /simplepie/library/SimplePie/Parse/Date.php on line 723

This is due to invalid pub data in RSS.
Format is `(MM/dd)`.