I'm not sure either the referee or the liner were in any position to see the handball as there were that many players in and around the six yard box, so maybe if Mattock hadn't put the ball into the net we maybe wouldn't even have got a pen.
Also it's an interesting point made about should their player have received a card of either colour, if the ref or liner did see it, being as we scored? Not sure of the ruling on that one but interesting point.