Moving back to a pushState entry that used ajax

I'm having an issue with the following situation.

1. User visits site
2. User clicks link which uses history.pushState to update the url
3. Partial page content loaded via ajax (using jQuery)
4. User clicks regular link which loads a new page
5. User clicks back to return to the pushState entry
6. The page now displays only the page partial that was retrieved via ajax

I've souped up a site using pushState for various things and the result is a shockingly responsive web app, but this issue is preventing me from using this.

Here's a sample of the code:

$('a').live('click', function(){
  history.pushState({}, '', this.href);
  popstate(this.href);
  return false;
});

popstate = function(url){
  $('#content').load(url);
}
window.onpopstate = function(event){
  popstate(window.location.href);
  event.preventDefault();
}

Notes:

• When placing an alert in the window.onpopstate function it appears that the event is NOT triggered at step 5. Is this a bug?
• The issue only occurs when ajax is used.
• I have had to separate the popstate function so I can call it after pushState. Is there a way to manually trigger the window.onpopstate event?