I think it's pretty obvious - because you hit it? If you're unhappy with the stick marks on your cymbal, you can easily remove them by cleaning or polishing.
it doesnt affect the sound or quality of the cymbal. it's normal. haha. try polishing if you can't get rid of the marks. some marks are pretty difficult to get rid of. i can't get rid of fingerprint marks on my cymbals with just cleaning. haha.