They should at the very least have asked you and given you credit. To not do so is rude, but probably not criminal.

But if you pitch a complaint all they have to do is change the page slightly, as in the order of contents, make some other minor changes, and they have essentialy stolen your product without stealing it.

You can be all hard nosed, but to what end?

Smile, and realize you are helping others indirectly. That's whats it's all about isn't it?