Thank you all for your comments. What I do not know is if the parent in 16D totally covered the infant with a blanket, I know there was a blanket being used but I was sitting in 17D I could not see directly in front of him without standing up during descent.. In which case the parent was actively deceiving the flight crew in a dark cabin.

Regardless, I will send a note to AA this weekend. To me this is something that needs to be reminded in training.