I am trying to query for all posts with a post format of 'quote.' I have added the post formats to my functions.php with

    add_theme_support( 'post-formats', array( 'image', 'video', 'gallery', 'quote' ) );

I have selected 'quote' as the format for the post in the admin. The last example under [Taxonomy_Parameters][1] shows how to display posts that have the 'quote' format but when I run it in my theme no posts are returned. Here is the code:

    $args = array(
      'tax_query' => array(
    	array(
    	  'taxonomy' => 'post-format',
    	  'field' => 'slug',
    	  'terms' => 'post-format-quote'
    	)
      )
    );
    query_posts( $args );

When I just query all posts and place 

    echo get_post_format();

in the loop it returns the word 'quote' on the front-end. Also, when I var_dump() the query I do not see anything in the array about post format. 

Does anyone know if it is possible to query by post format? If so how?

EDIT - See 5 comment under Bainternet's answer:
This is the code found on index.php of the twentyten theme of a fresh install trying to return format type quotes. I return 'no' instead of 'quote'. Can you see anything that I should change.

    get_header(); ?>
    		<div id="container">
    			<div id="content" role="main">
            <?php $args = array(
    				'tax_query' => array(
    					array(
    			  		'taxonomy' => 'post-format',
    						'field' => 'slug',
    						'terms' => array('quote')
    					)
    				)
    			);
          query_posts( $args );
          if ( have_posts() ) : while ( have_posts() ) : the_post();
          echo get_post_format();
          endwhile; else:
          echo 'no';
          endif;
          wp_reset_query();      
          ?>
    			</div><!-- #content -->
    		</div><!-- #container -->
    <?php get_sidebar(); ?>
    <?php get_footer(); ?>

  [1]: http://codex.wordpress.org/Function_Reference/query_posts#Taxonomy_Parameters