Thank you for your kind comment. Steemit has a bot, @cheetah, who is pretty good at detecting plagiarism when it's text that's been copied from another site. I think the problem here was that my post was too recent, so @cheetah didn't know about it yet.
Yes, that perhaps is the case. I thought that @cheetah only isolates those who get their articles from outside, but I won't be surprised if @cheetah comes in and gives this guy yet another warning!
I have seen Cheetah mentioning Steemit articles before. I'm not sure how long ago they should be posted though.
Thanks for the mention. Maybe longer nowadays - there's really a lot of content going on now that Steemit is catching up.