The best solution would be to add the time zone setting to the php.ini file so you don't need it on the page. That would prevent any errors moving forward.
You could also add the date_default_timezone_set() function call to the top of the globals.php file to prevent issues with this particular file. It is definitely better to do it in the php.ini file so you don't have to worry about it every time the date() function is used in php.