Glad you're loving Hype!
Yup that's it.
That is a 'query string'. It protects against this situation:
- Your server caches Javascript content for a period of X days
- You update your Hype document by re uploading your .js file to your server
- When reloading your Hype document, your server tells the browser 'don't re download this file'.
Having the query string in place ensures that the browser considers this file fresh -- the file is redownloaded each time someone loads your web page. If you find that reloading your page does not reflect your changes, you can either add that string back in, or change the filename of your Hype generated JS file.