Title appearing inconsistently depending on menu block location

I added a couple of strategic drupal_set_message() statements and have discovered the following: from the perspective of menu_block_block_view($delta = '') in sites\all\modules\menu_block\menu_block.module, the block title is present both times the block is rendered after menu_tree_build($config) has been called. However, by the time the sidebar block (only) is rendered in modules\block\block.tpl.php, the title is no longer present - thus the following conditional fails, and the drupal_set_message() I added (as well as the printing of the title, of course) is never hit:

<?php if ($block->subject): 
drupal_set_message(t('In block.tpl.php - subject: [%x]', array('%x' => $block->subject)), 'status');  
?>
  <h2<?php print $title_attributes; ?>><?php print $block->subject ?></h2>
<?php endif;?>

Anybody have a clue as to what would cause this behavior?

I ended up overriding block.tpl.php (as block--menu-block.tpl.php) so I could modify it in this way:

<div id="<?php print $block_html_id; ?>" class="<?php print $classes; ?>"<?php print $attributes; ?>>

  <?php print render($title_prefix); 
  // LEN begin added:  
  $config = menu_block_get_config($block->delta);
  $data = menu_tree_build($config);
  $title = $data['subject'];
  //drupal_set_message(t('LEN In block--menu-block.tpl.php - title: [%x]', array('%x' => $title)), 'status'); 
  // LEN end added 
  ?>
<?php if ($block->subject): 
  // LEN begin added:
  drupal_set_message(t('LEN In block--menu-block.tpl.php - subject: [%x]', array('%x' => $block->subject)), 'status');  
  // LEN end added
?>
  <h2<?php print $title_attributes; ?>><?php print $block->subject ?></h2>
<?php // LEN begin added: ?>
<?php else:  
  drupal_set_message(t('LEN In block--menu-block.tpl.php - had to get title: [%x]', array('%x' => $title)), 'status');  
?>
  <h2<?php print $title_attributes; ?>><?php print $title ?></h2>
<?php // LEN end added  ?>
<?php endif;?>
  <?php print render($title_suffix); ?>

Still hoping someone might have some insight into why this was necessary in the first place...

Thanks,
Lee