You were playing with pigman around his house, and now he is in yours? He teleported inside or what? There are two options. Maybe "playing around" means "playing Ventti", or a game bug. I think that you played Ventti, and you bet the house, and he won. That means, that your house will not open it`s doors for you anymore. All gets into one point. But from other side, after winning a house, he disappears from lake side cabin, and that`s all. I don`t remember him sitting in player`s house after winning it.