I have detected that when I save a draft the date of the post is not update when the post is published. For example: if I save as draft one post on 1-1-2014 and publish this post today, the date of the post is 1-1-2014.
Yes, the plugin doesn't update the date. Cause there are multiple issues with that when you use different post statuses on save/edit and when they publish again, the date changes to the current date. So it works that way as now and it'll not change.