Is it risky or obnoxious to ask a policeman this and why? Details inside.

If a fifteen year old boy is handcuffed for taking someone else’s property from their unlocked car is it risky for the boy to say to the police, “aren’t you going to read me my rights?” after being handcuffed? The boy in question was taken into custody for two hours for asking and then released. The police never said he was taken in for asking the question but witnesses say they were going to let him go before he asked them. Would you have asked them as a teen and why or why not?