Using the following code:
<?php
$mymood=get_post_meta($post->ID, "Mood", $single=true);
if(strlen($mymood)>0)
{
echo "<span>". the_author() ." was <strong>".get_post_meta($post->ID, "Mood", $single=true)."</strong> when he wrote this post</span><br />";
}
?>
... the author name displays twice. The blog has only one author.