I actualy need some more information to help you out with this question. But because of stackexchange "amazing" reputation system I can't comment yet. I thus will answer this question with assuming a lot of stuff, hoping it will help you. If not we can comment on this answer.
For more information on the general message you can go here link. It talks about why, how, and where the messages comes from.
Possible problem/solution 1:
The messages has been linked to the TinyMCE Advanced plugin several times. So if you have this plugin installed, please deactivate it and see if this solves your issue. This plugin produces the exact problem you are suggesting every time you navigate away from a post, even if the post has been saved or no changes were ever made.
Futhermore it is always smart to deactive all plugins, and see if this solves the issue. There might be a conflict with one of your plugins
Possible problem/solution 2:
When you navigate away from the post/page edit screen, do you use the back/forward button in the explorer? This might conlfict with "save" in wordpress.