If they wanted the source files, to be honest, I wouldn't give them to them. There is no legitimate reason for them to want the source files.
If I was a professional modeler then yes I would never just give away my source files, models or textures. Mainly because I'm getting paid for my time and work and would want the option to copy-write them. As far as I'm concern I'm a 'apprentice' age maker and the work that I'm doing is just something fun that I want to share freely to the community, all I ask in return is bragging rights.

Now, just copying the Blender file and your texture folder(s) will probably not work as the file paths of your textures are unlikely to be identical on your new machine, and you will end up with the dreaded "pink" objects syndrome when you open the Blender file on your new machine.
That's exactly what happen when I moved my age from my desktop to my new laptop, and this problem was what prompted my main concern about texture maintenance in ages. Now I know what to do.. and will be printing out the packing and unpacking method tonight just in case I do have to move my age to another computer again!
