query_posts 3.1 vs 3.0.5 - SQL differences

gistfile1.php

<?php
/*

this works, but is it right to separate out the two categories here? I thought I could include both cat ids in the first terms array, but it seems that if I do that, it pulls any post that matches either category instead of both.

*/
query_posts( array(
	'tax_query' => array(
		'relation' => 'AND',
		array(
			'taxonomy' => 'category',
			'terms' => array( 5629 ),
			'field' => 'term_id',
		),
		array(
			'taxonomy' => 'category',
			'terms' => array( 5623 ),
			'field' => 'term_id'
		)
	),
	'posts_per_page' => -1,
	'orderby' => 'title',
	'order' => ASC
));
?>