List not resorting when property changes in ember

I have made a little demo app where I have a tweet list and I am changing the number of favorites for a random tweet every 0.3 seconds, and the list is supposed to show the top 3 tweets based on favorites, but I can't get it to resort every time a number of favorites is changed for a tweet.

I have made a demo in jsfiddle with this application(show list has to be pressed to show the list).

In my sorting function I want it to check if favorites has changed for any of tweets

 App.AppModel = Ember.Object.extend({
                topTweets: function(){
                    return this.get('tweets').toArray().sort(function(a, b){
                        console.log("sort");
                        return b.favorites-a.favorites;
                    }).slice(0, 3);
                }.property('tweets.@each.favorites')
            });

This is where I change a random tweets favorites

  setInterval(function(){
                                   var iPosition = _.random(0, numTweets-1);
                                   var iFavorites = _.random(0, 4000);
                                    App.appModel.get('tweets').set(iPosition+'.favorites', iFavorites);
                                    App.appModel.get('tweets').set(iPosition+'.text', iFavorites)
                                }.bind(this),300);

The favorites are changing I'm just wondering why isn't the list resorting.