Random 302 redirects to my own site?

I’m getting random 5 character 302 redirects on my blog and it’s preventing my site being crawled properly and Facebook shares from working properly.

For example – this URL:

http://urlybits.com/2011/12/dude-chill-out/

In the browser it looks fine as it always make it back the proper URL but using a redirect checker I get this:

http://urlybits.com/PnVoM/2011/12/dude-chill-
out/

The 5 random upper and lowercase characters change every time. This is the output from the facebook object debugger –

Response Code: 302
Fetched URL: http://urlybits.com/2011/12/dude-chill-out/
Canonical URL: http://urlybits.com/2011/12/dude-chill-out/
Final URL: http://urlybits.com/RjPXQ/2011/12/dude-chill-out/

I’ve checked my .htaccess file and there doesn’t appear to be anything untoward in there. Could it be related to caching? I’m using WP Super Cache which is awesome.

Any help on this would be appreciated!