PeerIndex Code and "rodfaceplus3" Graphic Code in Text Editor After 3.3 Upgrade

I have no idea what is causing this to happen, but since upgrading to WP 3.3 a day ago, whenever I click on the New Post link, the following code appears in the text editor when I am in HTML mode:

 
<div id="ff_peerindex_tooltip"></div>
<img src="https://whos.amung.us/swidget/rodfaceplus3.gif" alt="" width="0" height="0" border="0" /><img src="https://bit.ly/sVbNRE" alt="" width="0" height="0" border="0" />

If I am in visual mode, just a broken image appears.

I thought it might possibly have something to do with some kind of conflict existing between 3.3 and the PeerIndex plug-in that I have installed in my Firefox 9.0 browser. However, even if I temporarily disable the PeerIndex plug-in, the above code is STILL appearing in the text editor window whenever I click on the New Post link in the Admin Toolbar.

Has anyone else experienced this, or know what it is, and why it keeps appearing in WP’s text editor window?

Thanks!