jquery 1.4 restoring page state on back button?

In Mac Safari 4.04 & Firefox 3.6, I am seeing page state being persisted on back button to page. I couldn't reproduce on jquery 1.3.2.

Here's a simple example:

<html>
    <body>
        <script type="text/javascript" src="jquery-1.4.js"></script>

        <a href='#content1'>tab 1</a> <a href='#content2'>tab 2</a>
        <div id='content1'>content 1</div>
        <div id='content2'>content 2</div>
        <script>
            $('a').click(function(){
                var href = this.href;
                href = href.slice(href.indexOf('#'));
                $(href).toggle();
                return false;
            });
        </script>
    </body>
</html>

1. Click on one of the anchors.

2. Goto another page

3. Click the browser back button

Result: One of the sections is still hidden.

Is anyone else seeing this? How is jquery doing this?