Gallery function not working on random post

Hi,
This is working great on my standard posts, but I’ve got a link on my homepage which takes the user to a random post. It uses
'orderby' =>'rand', 'showposts' => 1
in a query_posts array to do so. The post loads ok, but the gallery is missing.

I’m not really much good with PHP so looking at wp-simple-gallery.php I can’t see what the issue might be (maybe galleries are associated to posts by the post ID?!)

Any help would be great.

http://wordpress.org/extend/plugins/wp-simple-galleries/