NSXUL Folder?

For reasons unknown, I suddenly had a problem with getting Facebook to display an image thumbnail when I posted a link to my blog.

Then I noticed that there was a strange folder inserted into the URL that Facebook displayed.

I had pasted this into the status window:

http://pollywoginc.com/blog/2013/05/28/a-new-spin-on-tires/

But this is what Facebook is picking up and displaying:

http://pollywoginc.com/blog/2013/05/28/a-new-spin-on-tires/
http://pollywoginc.com/NSXUL/blo…

What the heck is that NSXUL folder doing in the URL? There’s no such folder on the server. How did it get inserted into the URL?

Is this a WordPress, Facebook or Blue Host issue? Is this a virus of some kind on the server or has my WP installation been hacked?

Thanks for your assistance.