I have a quite fresh install of 10.8.3 (not an upgrade - I reinstalled from scratch), and I have noticed that each time I wake up my MBP (13" early 2011) from hibernation, all applications have been closed (if applicable), or I can see warning popups asking if I want to shutdown the app (exactly the same as when you want to close your session with unsaved documents). I thereby concluded that os x sends a session closing signals just before going to hibernation mode. I have never seen anything like this !
Any help welcome!
Pro, OS X Mountain Lion (10.8.2), Early 2012, i7 2.7Ghz / 16GB Ram