Using Etags with ember-data

I am trying to implement some client side caching via etags and last modified headers; however, ember-data doesn't seem to be using the etags for the ajax requests. I only get 200 responses and never a 304. I don't see any ETag header being sent with the request headers.

When I make the ajax request multiple times directly from the browser address bar, I'll get 304 not modified responses after the first request, so I know the server is sending things back correctly.

Is there a configuration I need to set up to make this happen?

This is a CORS request, but I think that I have and I have exposed the ETag header:

Access-Control-Expose-Headers: ETag and the Etag header is sent back with the response.