He should have dropped the gun as he was told, rather than trying to hand it to him. Whether or not he was attempting to get closer to call Carl's bluff is irreverent. I'd be more concerned about a child pointing a gun at me than an adult, but that's just me. It seems like in most movies and such, whenever this is the case, the child is always taken advantage of and gets disarmed quite easily because they don't have the 'guts' to pull the trigger.
Maybe in the real world this might have some truth to it, but children often don't think about consequences and don't have the discipline adults to to judge certain minute actions. If Carl was an adult, he probably would have told the guy to stop moving and to drop it at least once more rather than just pulling the trigger in that split fight or flight second.
And this to me, is what separated Carl's actions from what someone like Rick would have done (police training, last resort, discipline, etc)
I don't think Carl really had the time to analyze everything in that moment, but afterwords, justified it by what he told Rick. It's probably true, and it could have easily been processed subconsciously in his mind then. This is a zombie apocalypse after all.
That said, I preferred the prior episode in terms of entertainment and tension. It seemed like they focused to heavily on Andrea's imminent demise, and the situation wasn't very original enough for me to be on the edge of my seat. The SAW movies pretty much revolve around the theme of what occurred in that room to some extent.
While sad to see a longtime member of the original group go, this is pretty much a show about people getting offed for the bad choices they make (most of the time, anyway), and Andrea had it coming for a long, long time.
I hope we can see a new scene in the future, as the Prison is getting a little stale, and without the threat of Woodbury, I have to wonder where the show's direction will go.
Some of the most exciting episodes were when they went to try and find out the cause of the infection. I'd like to see more lore involved about that.