It's something Gibson has to his game. We should be wanting our centre backs to be scoring more goals too.
....ideally they all chip in with a few. Our team model has Barry and McCarthy sitting deep, Barkley being key in linking that area with top third of the pitch. It takes a lot of effort for McCarthy in particular to also join in with forwards but I think it's something he's certainly looking to do (See Osman's goal v Lille). It just underlines the shifts Coleman and Baines put in.
There have been situations in the past few games where McCarthy has had a shooting opportunity around the edge of the box but passed it. Gibson on the other hand is much more likely to take a shot on. I do think McCarthy will add a few more goals to his game.