HARDDON : You shouldn't say the light isnt the problem, even though his plant is that size for 30 days old, the only thing I can think of is his light.. His light cant be that powerfull if that is a 30day old plant, it would only stretch if his light was way above his seedling.
If it's not the light, I would agree with HARDDON on the stale air, I would deeply suggest a fan for your plant.

NochowderForYou : Yes, HARDDON always *helps* people with there projects before we get to, MJ is tough to grow for some with little knowledge so HARDDON has to be a sexy beast with them, as you can clearly see .