The widget created by My Pinterest Badge http://wordpress.org/plugins/my-pinterest-badge/ has two links hidden with CSS:
<div style="clear: both; display:none ">My Pinterest Badge by: <a href="http://www.jafaloo.com">Jafaloo</a>. For Support visit: <a href="http://www.protechblog.com/tools/my-pinterest-badge.php">My Pinterest Badge</a></div>
Codes in the file pinterestloader.php line 153.
Basically the $showcredit option adds either none (hidden) or block to the CSS code. Since Google will still index display:none it’s a little underhanded and I assume not what WordPress considers not including the credit links when a user clicks don’t give credit!
I've emailed firstname.lastname@example.org with the above details as well.
For the record not only are you pilfering your users link benefit, you run the risk of damaging your own sites Google rankings if you get enough users using the plugin with the hidden links. Imagine a couple of hundred blogs with hidden sitewide links to those two websites, that could be 10s of thousands of links if the sites are large. Might want to keep an eye on your Google Webmaster tools page for a penalty warning.
I've had this problem with themes I develop where the credit links aren't hidden, because the themes are used on a lot of sites it generated hundreds of thousands of backlinks and Google didn't like it (a victim of my themes success). I would strongly advise if you add a credit link to only load it on the home page (so one link per site) and of course don't hide it from either Google or your users.