404 error when submitting a post?

I just received a 404 error after trying to submit a link post. And to make matters weirder, it shows up in my feed, but when I click on it to try and open the overlay I just get an endless loading wheel. If I open it in a new tab, the content of the post shows up for a second before redirecting me to the 404 page. Other posts appear to be loading fine, so I'm really confused! Here's a link to the post in question.