Shortcode for output of wp_get_archives displays at top of post

The default of the echo argument is true for wp_get_archives(). I think this would fix it:

// One Recent Post
function most_recent_post_shortcode() {
    return wp_get_archives( 'type=postbypost&limit=1&format=custom&echo=0');
}
add_shortcode( 'recent-post', 'most_recent_post_shortcode' );

UPDATE:
Previously: echo=false
Now: echo=0