The heating mechanism for the rear passenger seats won't stay on like the heated front seats. Once the heat on the rear seats are activated, they will warm up. But, after a while they switch off and you need to press the button again to continue heating them. They don't stay on continuously like the heated front seats.

Is this normal, or is there something wrong here?

Normal

You don’t want them in if no one is in the back , so they have a timer

Wot Andy said

Cool, thanks both