FeedBurner MyBrand WP Super Cache Problem

I’m running WordPress 2.3.2, using FeedBurner’s MyBrand (i.e. custom CNAME on my host). I recently got the WP Super Cache plugin to help me deal with increased traffic to my blog. I noticed that shortly after enabling the plug-in, my subscription link stopped working. What would happen when I clicked the link is my blog’s main page would be displayed and in the address bar I’d see the custom/forwarded feed.

My blog is at http://port79.org. I have my custom subscription link at http://feeds.port79.org/Port79, which used to be http://feeds.feedburner.com/Port79 before I started using MyBrand.

So my question is: how do I get WP Super Cache working along-side my subscription setup. I’m assuming that something gets translated into a static HTML file, which gets served instead of my feed.