Time difference craziness

[eluser]stuffradio[/eluser]
Some reason, when the time difference gets into the hours... it sometimes shows all the time differences as 354940.6 hours ago hours, etc. Here's the code I'm using:

Code:

$time = (time() - $rss->updated) / 60;
$hours = round($time / 60, 1);

$time is used for minutes, and $hours is the hours. $rss->updated is just a timestamp from the time it was inserted into the db. So why do I get these crazy hour differences sometimes?