I can't tell from the 2nd picture which branches those are in relation to rest of plant. Are those the branches nearest the wall or the ones closer to top where the new growth would be? One of my guesses would be that your watering may not be thorough enough and the harder to reach branches are not getting enough water especially if watering is just once a month. For a plant that size a good deep watering infrequently is better than small sips. Plants being near window usually dry out faster/more due to heat, sunlight and draft.
Another guess I have is before or during transplanting, some branches closer to the pot may have been injured/cut/crushed and the outer part of branch with curling leaves may be hinting so. You might want to follow the curled branches back to its origin and see if along the way there is damage?
