Hi, well this ones about my mum.. but she is a great parent, just became a bit forgetful sometimes..
Once when we were travelling to qld, when I was about 7, we had a stop in dubbo for a toilet stop.. I walked in with mum, came out and they had left me in the lou and kept driving!! It took them half an hour to realize I wasnt in the car!! That was really scary..
Another time was when she left my little brother in the shopping trolley and forgot to get him out after returning the trolley to the bay at coles. I was in the car with her, and as she was driving out I said.. are you forgeting something mum? LOL She felt pretty bad!!

I dont think what you did was wrong. Just like the others said.. its just a learning curve.