Well, what would happen is that if I'm ever to work on a project (game project that is) that takes place in an urban area (such as Half-Life 2 or other games), then I would like to use your brushes for textures and decals.
The problem will ofc be to remember telling you about this if such a project would arise and I wanted to use the brushes. But the problem would also be that I simply could not tell you about it due to legal reasons (NDA's - non-disclusure agreements). A developer bound to an NDA may not talk about the projects they work on until the project has been announced.
So... if I can't use your brushes then that's fine.
If I can use your brushes, there is a high possibility that you would not be notified of it.
I hope that clear things out. May I use your brushes in my field of work?