Hello, I'm one of the developers of our widgets.js file so I took a look into this for you this evening.
Firstly, the hub.html frame is an event passing bridge, allowing the buttons and widgets to communicate events (such as follows and tweets) back to the parent page. That's why it's there.
The positioning of the hub frame, however, is purely vertical (negatively positioned above the top of the page. It should not cause any change to any dimensions of your page, and certainly not to your page width.
Could you please follow up with which web browser you're seeing this issue appear in, and I'll try to reproduce it again in the same environment as you're testing.