Those plants are small and lanky for a month old. They also look like they could be heavily Sativa... brick bagseeds?
BUT they are growing so you're on top of it.
Give them more light and notice that they are getting a little pale... combiation of poor light and that they are ready for some fertilizer.
Get at least a 100w equivalent CFL swirly light on that thing like pronto and you will notice better growth fast.