It's because a link is too long...
http://simplevegancooking.wordpress.com/2012/10/06/creamy-cheezy-leek-and-spinach-pasta-sauce/ has already been cut down to simplevegancooking.wordpress. but needs to be cut down more.
If you find line 436 in rotating tweets:
if(strlen($displayurl)>29) $displayurl = substr($displayurl,0,29)."…";
and change it to:
if(strlen($displayurl)>24) $displayurl = substr($displayurl,0,24)."…";
That should solve your problem.
Alternatively, change:
$after[] = "<a href='".$url->url."' title='".$url->expanded_url."'>".esc_html($displayurl)."</a>";
to:
$after[] = "<a href='".$url->url."' title='".$url->expanded_url."'>".esc_html($url->url)."</a>";
and that should also solve your problem!