Apache making the session time out longer

do you also have set session.cookie_lifetime = 0 ? and maybe somewhere in your scripts or some included scripts the session lifetime is set to another value?

The default "0" value means that the cookie stays alive until the browser is closed. This is also the default value, if not set in php.ini. Source: http://www.php.net/manual/en/session.configuration.php#ini.session.cookie-lifetime