This is due to your browser caching the page.
When the browser recieves the page, it stores a copy of the recieved page with itself--so if you hit the back button, you get to see this cached page. You can test this by opening a random page, clicking a link on it, disconnecting yourself from the Internet(noooo!), and hitting 'back'--the page will still load.
On the other hand, new stuff which happens to the page is not cached. IIRc, sombrowsers do cache normal JS/etc, but maybe not websockets/AJAX (not sure if thus)
So this is a browser issue, not an engine issue.
Update:
I'm quite sure the realtime updates work on a "push a new change as it comes along" system. To fix your bug, the behaviour will need to be changed to "push the 'new changes' list every xyz seconds", or "AJAX-fetch the question list on page load". Both solutions blow up bandwidth (former more than the latter), and the latter is just redundant.
Update2: OK, there is a server-side cache issue. Can has fix?