So skydiving has always been a dream of mine, and after six years I finally am able to go forward with it. I went through my aff 1 over the weekend, and loved every minute of it. I did my COA, three practice pulls, second COA, forward movement, back to arch, and was responsive to hand signals; however, when 6000 came up I locked on and went blank, next thing I know I feel my main pulled and I'm under canopy at 4500. I shake my daze away and remember time to canopy check, and lined up for holding area. Apparently they were giving me pull sign, and trying to pull my arm back for pull. I felt completely fine up until 6000, is this a case of sensory overload? This was my first jump, and I'm confident I will stay altitude aware for my next jump. Still, I worry that it could happen again even with confidence, since I've never experienced it before. How common is something like this?