Stannis is smart enough not to go on his own to confront Tywin. ;) Also, I'm fairly sure Tywin knew and chose to ignore it. I doubt that someone as smart as Tywin didn't know.

I'm not sure he will ever be mentioned again, he'S such a minor character. *sigh*
From what I've seen, people just think he's pathetic because everyone in canon talks about how awesome he is, but the only thing we've ever seen him do is try to kill a little girl and he didn't even manage to do that, so he can't be that badass. Which is utterly dumb reasoning, imo.