Recent license change?

[Karol Suprynowicz]

Hi!
After updating GNU Parallel included in main Debian testing repository to 
version 20141022+ds1-1,
a new message started to appear with every GNU Parallel run:

"When using programs that use GNU Parallel to process data for publication 
please cite:

  O. Tange (2011): GNU Parallel - The Command-Line Power Tool,
  ;login: The USENIX Magazine, February 2011:42-47.

This helps funding further development; and it won't cost you a cent.
Or you can get GNU Parallel without this requirement by paying 10000 EUR.

To silence this citation notice run 'parallel --bibtex' once or use 
'--no-notice'."

According to both GNU Parallel website and manpage it is distributed on GPL 
v3 license. The notice implies commercial license when using GNU Parallel 
for scientific publications.
I've created Digital Image Correlation software package that I intend to 
distribute on open-source license (probably also GPL v3), and I'd like to 
use GNU Parallel for some parallel data processing - it's very useful tool. 
In such case clear licensing terms are very important - I don't want to open 
myself or someone else to the possibility of ligitation.
What is the current license for GNU Parallel? Is it compatibile with GPL v3?

I've not used GNU Parallel for any publications and not used it at all since 
the message appeared after update.

Regards,
Karol Suprynowicz