Is the JS token non-free?

Is there an exception to the piece of Javascript code that Piwik outputs from the GPL? I would like to use Piwik for my website but am concerned that I will be required to release the source under the GPL.
A program that includes substantial text from itself in its own output (like gcc or bison) forces the output to be under the GPL unless an exception is provided. Is there a bison-like exception for the Javascript code?

The piwik.js & code snippet is BSD so no problem to use it for you

You have nothing to worry about. The Piwik developers have already given this a lot of thought. In your Piwik folder, you’ll find a “LEGALNOTICE” file that covers all the licenses involved.

The generated tracking tag is public domain. Use it, abuse it, do what you want with it. It loads piwik.js and makes three function calls.

“piwik.js” is released under a very liberal license – a simplified BSD license.