"leaf Curl" Help Please

I have 1 little plant left out of 3 & im a bit worried about it.

Im using

Greenhouse AMS Feminised Seeds
Potting compost
10% perlite
10% fine sand
Natural light (Window sill)
Planting outside when hardy enough(Greenhouse)

The PH is correct at 5.5-6 but the leaves are gradually curling & drying slightly...The new growth is ok for a few days then starts to curl...Im watering every few days when soil drys out.

Any advice would be greatly appreciated

Thanks

Hmmm . .. kinda looks as tho it almost dried out too much once. Since it's so early in the grow, and the next set of leaves look a little better, I'd guess it will be fine?
Good luck.

Thanks for reply MrFishy.... It was left in direct Sunlight without a fan (Powercut) a few days ago when i was late home... Maybe that done the damage....