Oh My God, NO! Man, this had me laughing XD Sorry, but you're not an idiot, it's happened with me too. Only I copy pasted something...worse a hundred times haha XD It must have been because of '<3' which we generally use (:
It has something to do with symbols, more specifically ">" and "<". At least that's what I got told a few months ago by kitsch who was lovely enough to point that out.