Hrqls: By default, in a money game, you only get double/triple points for a gammon/backgammon if the cube is on 2 or more. This is called the Jacoby rule.

I also downloaded gnubg, and I don't think it's playing very good. I played a money game for a while, and it didn't take me very long to get a 132-16 lead. And I'm not a good backgammon player at all.