[LAU] [OT] creative commons non-commercial licensed music - ask for advice

I received an email from a film producer (based in Los Angeles, probably an indie studio) in which he wrote that the director of a movie they're just finishing (they're at post-production stage) is interested in using two tracks of mine, 'Balloon' (http://www.cesaremarilungo.com/media) and 'As we grow older' (http://www.cesaremarilungo.com/media/the-moon-ep). I released these tracks under a non-commercial Creative Commons license: http://creativecommons.org/licenses/by-nc-nd/2.0/deed-music. In the past some of my music has been used for some short films, but these were clearly non commercial projects or film schools thesis. Has anybody some experience on this topic? What should I do? Should I re-license these tracks? Can I just make them a written permission? Or should I ask for some kind of royalty (or would it be ridiculous, also considering that AFAIK Gyorgy Ligeti has never been paid for its music on '2001 A space odyssey' :-) )? Thanks in advance, - c.