Yes you really need to watch the watering when they are this young. How often do you water? and how much each time really it just needs a little bit like every other day at this stage. Watch the nutrients as well these really are two of the most common mistakes made by beginners, I am a beginner as well but read that beginners always give the plants too much water and nutrients because they love them so much. only thing i dont understand is how youre suppose to see if it is underwatered.... hmm. And if you have good soil then maybe dont give it more nutrients at the moment. If you have a digital camera can you send some pics please so we can point the problem out to you (if there is one).