random imgur image selector (quite a dirty approach) issues:returns ocassionaly 404's while the image in fact exists

gistfile1.php

<?php

//random imgur image selector (quite a dirty approach)
//issues:returns ocassionaly 404's while the image in fact exists

$str = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';

while(true) {
        //variables
        $shuffled = str_shuffle($str);
        $trimmed = substr($shuffled, -5);
        $header = get_headers("http://i.imgur.com/" . $trimmed . ".jpg");
        if(($header[0] == "HTTP/1.0 200 OK" || $header[0] == "HTTP/1.1 200 OK") && array_search('Content-Length: 503', $header) == false){
                header('Location: http://i.imgur.com/' . $trimmed . '.jpg');
                unset($trimmed, $header, $shuffled);
                die();
        } else {
                unset($trimmed, $header, $shuffled);
        }
        }
?>