Contributor appearing in list of authors

I’m using the following code to output a page that shows a list of all of my 20 or so authors. It’s working fine, except for this weirdness: I promoted a contributor to an author as a test, then put him back to contributor. However, he’s still showing up on this list, though none of the other contributors are. I’ve double-checked that his role has indeed been set back to contributor. Is there something wrong in my code that’s causing that?

Here’s my code:

<?php
/**
 * Template Name: All Author Archives
 */

get_header();?>
    <div id="all-authors-archive">
      <h1 style="font-family: 'Noto Sans', sans-serif;"><?php the_title(); ?></h1>
<?php
// Arguments to pass to get_users
$args = array( 'orderby' => 'post_count', 'order' => 'DESC', 'who' => 'authors', 'exclude' => '1, 31052', 'post_type' => 'post', 'post_status' => 'publish' );
// Query for the users
$authors = get_users_ordered_by_post_date( $args ); ?>

<?php
// Loop through all the users, printing all of their posts as we go
foreach ( $authors as $author ) { ?>
      <a name="<?php echo $author->user_nicename; ?>"></a>
      <div class="author-posts-wrapper" id="author-<?php echo $author->ID; ?>-posts-wrapper">
       <div class="author-posts" id="author-<?php echo $author->ID; ?>-posts">
          <div id="author-page-name"><a href="<?php echo get_author_posts_url( $author->ID ); ?>"><?php echo $author->display_name; ?></a><br>
          </div>
          <div id="author_bio"><?php echo $author->description; ?></div><br>
 <div id="authors_recently"><em>Recently: </em>&nbsp; <?php
  // Set up a Loop, querying for all of the current user's posts
  $args = array( 'author' => $author->ID, 'posts_per_page' => 1 );
  $posts = query_posts($args);
  // Now that we have the posts, simulate a Loop here or use get_template_part
  // if we already have the output in another template, like:
  // get_template_part( 'loop', 'all-authors' ); // Pulls in loop-all-authors.php from theme
  if ( have_posts() ) : ?>
       <?php while ( have_posts() ) : the_post(); // Print whatever we want for each post - for now the title and date ?>
         <a href="<?php the_permalink(); ?>" title="<?php the_title(); ?>"><?php the_title(); ?></a> &mdash; <?php echo get_the_date(); ?>
    <?php endwhile; ?>
        </div><!-- #author-post-list -->
  <?php else: ?>
          <p>This author has not yet published any posts</p>
  <?php endif; ?>
        </div><!-- #author-posts -->
      </div><!-- #author-posts-wrapper -->
<hr><?php } // End looping over all users ?>

    </div><!-- #all-authors-archive -->
<?php
get_footer();
?>