You Sir are correct are the leaves only coming from the main stem then yes this is from Fimming the top. If all other leaves look healthy then that's it. Not much you can do about it and nothing bad is going to happen but your plants do look thirsty unless this photo was taken just after the lights were turned on I would say I see slight wilting too. Though I'm not botanist all together plant looks healthy your doing great best of luck for the rest of the grow.