date time problem

I always hate dealing with date/time stuff in php - never get it even close until an hour or two goes by.... anyway I have this: // get two timestamp values $exp_time = $_COOKIE[$applid."expire"]; $curr_time = time(); // get the difference $diff = $exp_time - $curr_time; // produce a display time of the diff $time_left = date("h:i:s",$diff); Currently the results are: exp_time is 06:55:07 curr_time is 06:12:03 the diff is 2584 All of these are correct. BUT time_left is 07:43:04 when it should be only "00:43:04". So - where is the hour value of '07' coming from?? And how do I get this right?