The bug affected SpriteFont rendering on iOS devices with retina displays. If you have released a game using SpriteFont and this code (including if you are in the pre-release program), please be sure to update your game in the App Store.
Sorry about that 🙂 Remember that ExEn is not yet officially released. You could say that it’s in “beta”. So these things will crop up occasionally. To get bug fixes as soon as they’re available, consider joining the pre-release program.