I agree with
@growinggrannie. Your leaves look "plump" and they've curled at the sides - these are classic overwatering symptoms. Cut back a bit and they'll recover quickly. Best way to test if they need watering is to lift the pot regularly - you'll know from the weight alone after a couple of days of doing this.
You are right about the RH though: I would recommend keeping this up at 60-70% and not letting it drop as far as 45% if you can. Not the end of the world, just not ideal during veg.