Not insane at all. Child seats should be rear facing for quite a while and if the kid is asleep, they are not making any sounds. A big deviation from your routine can seriously fuck up remembering basic things. I personally have a mirror strapped to the rear headrest to avoid anything like that since I can see her every time I check my rear view mirror. But I’ve had people warn me how dangerous those are because it is an extra thing to break off in an accident. I’d rather take that risk than accidentally leave my child in a hot car.

From the Pulitzer article (please read it):

Diamond is a professor of molecular physiology at the University of South Florida and a consultant to the veterans hospital in Tampa.[…]

“Memory is a machine,” he says, “and it is not flawless. Our conscious mind prioritizes things by importance, but on a cellular level, our memory does not. If you’re capable of forgetting your cellphone, you are potentially capable of forgetting your child.”

“The quality of prior parental care seems to be irrelevant,” he said. “The important factors that keep showing up involve a combination of stress, emotion, lack of sleep and change in routine, where the basal ganglia is trying to do what it’s supposed to do, and the conscious mind is too weakened to resist. What happens is that the memory circuits in a vulnerable hippocampus literally get overwritten, like with a computer program. Unless the memory circuit is rebooted – such as if the child cries, or, you know, if the wife mentions the child in the back – it can entirely disappear.”