There was quite a good article recently about how quotes turn into misquotes and eventually proverbs: http://www.chronicle.com/article/Who-Really-Said-That-/14155...
There are basically three kinds of Wrongly Attributed Statements. WAS I is an adaptation or composite of a statement or statements from someone or several people, who may or may not be famous. WAS II is a statement that was uttered, as is, by someone, often not famous, that has come to be widely attributed to someone else, invariably more famous. WAS III was never uttered by anyone, at least not that we know of.
So this was a WAS I. :)
Edit: Actually, this article is better than quite good. It's the best one I've seen on the topic and quite fun and one could even call it definitive.
Edit 2: Ok, https://news.ycombinator.com/item?id=6445595.