I sent an email based on the comment you left on my site, but just in case someone else runs into this, I need some more detail. I have also rolled back the stable build to 0.63 as a precaution.
Due to a conflict with the very popular WordPress SEO plugin, I had to change how the short code was processed. Previously the plugin would try and detect on the fly when the post type was a form and would insert the appropriate short code on the fly which the short code processor would then process. In some cases, this ended up happening multiple times which was obviously a problem.
This update to the plugin stores the shortcode for the form as the post content when the form is defined (the post editor field isn't visible when defining a form because it isn't used) upon the publish action. The plugin will also update any forms with their shortcodes as sort of a "house keeping" step. However, in both cases, the post is checked to ensure it is a Google Form post and not a regular post or page before updating the content.
I've had quite a few people test this version without reporting anything like you've reported but just to be safe, I have rolled back the stable tag to the previous version.
What else can you tell me about your site? What other plugins and/or themes are active?