If they are turning around and coming after you, that is a separate issue, otherwise, I dont see that you would be able to do more than let them know (and presu

If they are turning around and coming after you, that is a separate issue, otherwise, I dont see that you would be able to do more than let them know (and presumably they already do) that they are using your code. If they were to claim that you or anyone who had used your code is infringing their copyright, then its more in the realm of a frivolous lawsuit, that you might have to defend yourself against. It may also be just a sloppy oversight. I have worked places where it is standard practice to include a copyright notice with the code, and that use appropriately licensed open source components. Might it just be a matter of them applying their corporate policy without any particular malice?