For some reason, I messed up the installation of WP SuperCache and it was serving old versions of the site to some visitors. I’ve fixed this temporarily by disabling WP Super Cache. I will update this post when I get it fixed for good.
On a related note, I also tweaked the RSS feed last night, so if you got duplicates or something like that in your feed, it’s all my fault. Sorry! But luckily, these changes should make your RSS experience that much better :)