When calling logger->notice() don't use t()

This module has

watchdog('user', t('Session closed for %name - Invalid IP. '.$ip2check, array('%name' => $user->name)));

but this should be

watchdog('user', 'Session closed for %name - Invalid IP: %ip_address', array('%name' => $user->name, '%ip_address' => $ip2check));

Note: Injection of HTML via header could be possible if an HTTP header for IP address is configured, but the output is filtered by filter_xss_admin() so should not be a XSS vulnerability.