Gallery Shortcode Pulling ALL images in do_shortcode

I have a site that has used this code for well over a year and displayed just the current post’s worth of images in a custom-post-type-single.php template.

<?php echo do_shortcode( '[gallery columns="3" size="listing-gallery-thumb" link="file"]'); ?>

I updated to WP 3.6 and then to 3.6.1 within a couple of days of each release, and today the client came to me and these galleries were displaying ALL images from all posts.

I added a post id to the code like so

?php echo do_shortcode( '[gallery columns="3" size="listing-gallery-thumb" link="file" id='. $post->ID . ']'); ?>

And that fixed the error, but all of the documentation i can find still says thet the default behavior without the post ID should be to show only the current post’s images.

Has this changed with 3.6 or 3.6.1?