I'm new to the competitive shooting world, but it sounds to me like muscle memory. Same thing for us in the military world. We train,train,train,train,train,train,train,train,train, etc.. then all of a sudden one day the poo hits the fan (buzzer goes off) and you just react. When it's all said and done with you don't remember much, but you're either alive at the end of the gun fight or just shot well in your stage. Just remember though; practice doesn't make perfect. Perfect practice makes perfect. IE: when you practice make sure you take the time to do it right and when " the poo hits the fan" it'll be right then also.
Congrats on your first shoot