Sometimes in comments are answers to the question. What should I do if somebody used Copy&Paste method to write an answer, which is built from comments' content?

  Should I mark that answer as the plagiarism and give it to the moderators' attetion?

Sometimes comments are answers to the question. What should I do if somebody used the copy & paste method to write an answer which is built from comments' content? Should I mark that answer as plagiarism for the moderators' attention?