Is Copying the Finest Form of Flattery?

What's the best course of action when you feel that someone has plagiarised something you have written? I have found that someone has used my subheading I Love My City Because... and changed some but not all the words in it, on the top of their blog . I feel uncomfortable about this despite the fact that they have linked to me. Is this reasonable? How do I address it? In some respects this is bound to happen on the web and ideas are probably endlessly regurgitated and used in differing forms across the blogosphere but I feel that my writing is my own and would hate someone to read my subheading and think I had copied it from somewhere else. Maybe I'm just being paranoid.