first of just make sure you do not have any bugs! If there are none it almost looks like they were a little root bound before they got re-potted and that can cause a bunch of symptoms including what is seen in your pics so if the new growth is not affected and stays growing good that was most likely the issue. Also you may be onto something with the pH👍, so make sure you pH is good on your runoff just to be safe and if you can try and lower your temps a little 81 isnt that bad but if you can try for around the 75ish range. Now with the leafs curling down that could be under/over-watering feel the weight of the pot when its dry but not to the point the plant is wilting. Then after you give it a watering feel the weight makes it a little easier to make sure your not over-watering. Good luck😊 Hope this helps. If you have any other ?'s dont hesitate to ask my friend👊