What are your Temps and RH sitting at?
I encountered these symptoms a few weeks ago, contributed it to low humidity, I was resting at 35%. Once I increased RH curling and canoeing stopped in a few hours. I’m pretty new to growing, thats just what helped me.
I’m sure some vets will pop in shortly.
Best of luck!
One of the experts here will be able to help better if you fill out the support ticket below. I notice you already posted this under another topic?
COPY/PASTE the below list into your forum post.
Answer these simple questions the best you can.
If you do not know, or do not use something; Just say so; Or post
NA (non applicable)
- What strain, Seed bank, or bag seed
- Method: Soil w/salt, Organic soil, Hydroponics, Aquaponics, KNF
- Vessels: Pots, Grow beds, Buckets, Troths
- PH of Water, Solution, runoff (if Applicable)
- PPM/TDS or EC of nutrient solution if applicable
- Indoor or Outdoor
- Light system
- Temps; Day, Night
- Humidity; Day, Night
- Ventilation system; Yes, No, Size
- AC, Humidifier, De-humidifier,
- Co2; Yes, No
Always try to upload a clear picture of any issues you may have to allow the community to assist you.
Add anything else you feel would help us give you a most informed answer should be included. Feel free to elaborate, but short and to the point questions and facts will help us help you in a more efficient manner 
Thanks!