Strange Facebook favicon behavior

Perhaps this is nothing, but I might as well document it anyway. So I was browsing my news feed a few moments ago when I noticed MG had liked a few tumblr posts. So not one to ignore, I clicked through.

I opened a few extra tabs but when I opened the second thumbnail, a link to Path’s blog, I noticed the Facebook favicon in the corner.

This is the link from the image above:

http://blog.path.com/post/26045642389/pathspeaksmorelanguages?og=1&fb_action_ids=10101751342721963%2C10101751341574263&fb_action_types=tumblr-feed%3Alike&fb_source=feed_opengraph

I figured it was a bug, but then again this is Facebook, there’s probably something a little more sinister at work here. I opened a few more links to see if they behaved similarly. Strangely, they do display the Facebook favicon, but only for a fraction of a second before it’s swapped with the proper favicon. It’s barely noticeable. Chrome shows that they are links to external websites, so why does it load Facebook momentarily?

This is probably totally normal, but this is Facebook, no doubt there’s something sleazy at play here. It’s probably no different to the way Twitter force a t.co route, either way I’m keen to learn more about it. Maybe one of you guys can shine a light on this?

Further Reading thanks to @jixop

How is facebook tracking our (outgoing) URLs?
http://mattiasgeniar.be/2011/03/30/how-is-facebook-tracking-our-urls/

The insanity of URL shorteners and tracking
http://mattiasgeniar.be/2012/06/18/the-insanity-of-url-shorteners-and-tracking/