In WordPress 3.6 (which I realize is not yet supported), the_title() adds <span itemprop="name"></span> around the title, inside the h1 tag. Unfortunately, that means that any service to which the plugin is trying to pass the title (Reddit, Tumblr, email etc.) is getting caught up at the quotation marks, and is working incorrectly. This is probably already slated for fixing in the next version, but I wanted to bring it to your attention just in case you hadn't noticed it yet.
Thanks for what looks like an otherwise great plugin. :)