It may not have been done for that reason alone. NIHS is pretty common among hackers:

http://en.wikipedia.org/wiki/Not_invented_here#In_computing

It also seems to me that a new language for this exact purpose is unlikely, however, it could very well be a proprietary or otherwise unknown language that may have been built for another purpose (internal company, domain-specific development, etc) and not often seen in this context.