My ember APP adds unexpected record after displaying

when I click in post title ('Test post') here and when I return to post's list I have unexpected empty record. This is a strange behaviour. I have simple construction:

Ember model (post.js):

import DS from 'ember-data';

export default DS.Model.extend({
  title: DS.attr('string'),
  slug: DS.attr('string'),
  intro: DS.attr('string'),
  body: DS.attr('string'),
  created_at: DS.attr('date'),
  updatedAt: DS.attr('date')
});

Ember routes:

this.route('posts', {path: 'blog'}, function() {
    this.route('post', {path: '/:post_slug'});
  });

index.js - for list

import Ember from 'ember';

export default Ember.Route.extend({
  model() {
    var posts = this.store.findAll('post');
    return posts;
  }
});

post.js - for single post

import Ember from 'ember';

export default Ember.Route.extend({
  model(params) {
        return this.store.findRecord('post', params.post_slug);
    }
});

Ember serializer:

import DS from 'ember-data';

export default DS.RESTSerializer.extend({
  primaryKey: '_id',
  serializeId: function(id) {
        return id.toString();
  },
  extractCreateRecord: function() {
    // do nothing
  }
});

and I use RESTAdapter.

Express API:

app.get('/api/posts', function(req, res, next) {
    Posts.find(function(err, response) {
        posts = response;
        res.json({posts: posts});
    });
});

app.get('/api/posts/:url', function(req, res) {
    Posts.findOne({slug:req.params.url},function(err, response){
        post = response;
    res.json({post: post});
    });
});

Anybody can help me?