Domain Mapping and HTTPS

When I turn debug mode in WPMU, I get the error:

Notice: Undefined index: HTTPS in /var/sites/t/tbreak.com/public_html/wp-content/mu-plugins/domain-mapping.php on line 503

Notice: Undefined index: HTTPS in /var/sites/t/tbreak.com/public_html/wp-content/mu-plugins/domain-mapping.php on line 473

Notice: Undefined index: HTTPS in /var/sites/t/tbreak.com/public_html/wp-content/mu-plugins/domain-mapping.php on line 537

All three of these lines have the following code:

$protocol = ( 'on' == strtolower($_SERVER['HTTPS']) ) ? 'https://' : 'http://';

I'm getting a lot of backed issues and trying to figure out anything that can cause the slowdown/timeouts. Could this be one of the issues and if yes, what do I need to change to get rid of it.