Hi Phill.
I would be cautious about putting another super on especially uf it's getting cold, more space for the bees to try and keep warm. Look at population, if they are cramped, then maybe. Are there still drones. If not they may be reducing population and I would wait for a couple of weeks.
If just pollen then thats good as come spring they will need it, protein for the building of young.
Regards,
Aaron.