I looked at the site with the Firefox extension Firebug, and got the sidebar to pop up to the right hand side by setting the following CSS rules:
It looks as if something changed (maybe inserting the gallery?) so that the width of your #container div (which includes the #content div) plus the width of the #primary div (which has the widgets) is greater than the width of the #main div — so the browser had to put #primary after #container instead of beside it.
You should be able to fix it by adjusting the CSS file. Best wishes!