I posted an answer, then decided I wanted to edit in a quotation. I did so, but it resulted in a new answer instead of an edit to my original answer. This was in the mobile view on Safari (iOS 8.1.3).
I'm certain that it was submitted as an edit, not a new post, since to create a new post I would have had to start editing my original answer, copy its text, scroll down and click "Add Another Answer", paste in my text, and then make the changes, all without realising what I was doing. I did not do something so elaborate and wasn't sleepwalking through the UI, I just used the edit link under my first answer.