I just noticed this too. Can you verify that you were hacked? I took this line out:
add_action('wp_head', 'cred');
function cred(){
echo '<div align="right"><small><a href="https://www.packages-seo.com/">seo</a></div></small>';
}
This plugin looks pretty awesome other than this guy trying to post a link back to this packages-seo.com site.