Metabox not visible for non admins

Hello,

I’m using this code in functions.php to show posts in admin backend only from author currently logged in:

function posts_for_current_author($query) {
	global $user_level;
	if($query->is_admin && $user_level < 3) {
		global $user_ID;
		$query->set('author',  $user_ID);
		unset($user_ID);
	}
	unset($user_level);
	return $query;
}
add_filter('pre_get_posts', 'posts_for_current_author');

From version 3.3.9 ACF metabox is not visible any more for contributors.

Is there any other solution except to remove this code from my theme functions.php

Thanks!

http://wordpress.org/extend/plugins/advanced-custom-fields/