Strange behaviour in Sortables

Strange behaviour in Sortables


If I place a script tag within a sortable such as:
<div class="portlet">
<div class="portlet-header">News</div>
<div class="portlet-content">Lorem ipsum dolor sit amet
<script type="text/javascript">
alert('Why am I called twice?');
</script>
</div>
</div>
...in the portlet example:
http://jquery-ui.googlecode.com/svn/trunk/demos/sortable/portlets.html
It seems to be called exactly twice but no more. Once on page load,
and once
after the first drag (whether the position of the portlet changes or
not).
Does anyone know why this occurs?
Thanks for your help,
-- Loren