Yes you do. The answer is - you're not sane if you think a post with a quote inside quote tags can be reported as plagiarism. But you're welcome to try.
Mods are not sane too to ban such kind of report when it was being qouted meaning to say that it is not being owned by the one who posted it. Anyway, I think there is no need to report that kind of post and it is a common sense. It should not be to avoid also getting bad report.