I think it needs more light, if it's possible then you should invest in a bulb to stand over the plant..
I'm not an expert and I'm not sure if that's the solution and I don't know which bulb to use, but that's the most logical problem, not enough light.

I'm going to agree with Maxim, your plant is getting leggy and is searching for better light. A lightbulb would be appropriate, or a window with more hours of light per day( Here in the states it's a south or west facing one, but I don't know if that's flipped for you guys below the equator :P )

Otherwise he seems fine.. you might have to decapitate him though, because once a plant starts going leggy, it won't shrink back to 'normal' size. But hey, if you do that, you'll end up with more of these little buggers! :D

I'd also change out the mix if it's crusty hard. It may not be letting any water penetrate the center. Peet based mixes can dry out and become impermeable, later. You want an open lose mix. And yep more light would keep it form elongating in a quest for more.