Looks like this was related to a fix we made for iOS to prevent caching of non-cacheable requests. This fix was updated to only apply to iOS 6 in 2.3.0: https://github.com/enyojs/enyo/commit/73ade2a9dd68deb2f4a4db548c45e2c27104632f
Per the comments in the fix, you can use the header property to specify an object with cache-control: null, unless you're planning on upgrading to 2.3.0. :)