Don't feel bad! It happens to the best of us. One time we took Franklin to Petco and my bf forgot Franklin's leash. You see, I usually put him in the cart and then hold onto the leash so that he cannot jump out. Well we figured he would be okay if we just watched him closely. Well as we were walking out to our car, he jumped out of the cart and landed on the pavement. He shrieked and was hesitant to let us touch him. Of course we rushed him to the e-vet, only to have him tell us that Franklin was FINE. 46 bucks out the window..
Better safe than sorry, I guess. We definitely learned our lesson!