Alright, I'll take a stab at it. It looks a bit like underwatering. Basing that mainly on that right leaf curl. I'm by no means an expert, but whenever I've seen curling along the main leaf stem (as opposed to the leaf tips curling under the leaf) it has been underwatering.
They say that it is always better to underwater than overwater, though. You can tell when to water the weight of your pots, but just play it safe a get a water meter.