Lower leaves drooping and curling

Hi, it seems that your seedling is living in a slightly too dry environment, look for VPD online and find out about the subject to understand the best combinations of temperature and humidity for each growth phase (At your temperature, after 5 weeks I recommend a 50 % humidity). However it seems that your seedlings are not absorbing enough oxygen from the roots for some reason (Too much water, root rot, soil saturated with fertilizers), check the EC and pH of the water flowing out of your pot. Good luck!

There were transplanted about 4 days ago.

You don't say WHEN you transplanted them but I feel this is simply the plants needing time to recover from the transplant... It's also possible the soil is a little too hot for them unless they were in that same soil before... and finally, that temp is not good - needs to be at least 68F if you can manage it... purple strains like colder temps and will react favorably by increasing their colors but at this stage, you run the risk of stunting the little ladies... Good luck!