Signature lines?

Hello, I was wondering what you all thought of signature lines of some authors? An author I love, likes to use a certain line in a certain situation. I can't say I have read it in anyone elses books, but can someone claim to "own a line" if you will? I am not sure if I can include the line/situation in question, so comment if you want some more detail. Just wondering if it ends up being a "you stole my line!" Situation.