Without the obvious negative, curling can be a sign that your right on target. There's too many variables tho and a lack of description. Top new growth curling is fairly normal tho.

Here is one photo.

Mine did that last year and I never did figure it out, but they were fine. It could be due to the cold.

It's a bit spindly. Looks as if it needs more light.

Doesn't look too bad. Can you plant it outdoors?

Its near the window. Its overlooking east, so the plant gets sun all the morning.

The temperatures are around 19-24,most of the times 21C. (nearly 70F).

I water them from the bottom.

I bought the soil-seedling mix, i think good quality.

I could plant it outdoors. Ive already planted one tomato plant in the garden and its doing well.( I put them under plastic galones of water, which makes a good environment.)

Here are some more photos:

This is the thing, that i wonder what is.

Anyway, they are healthy at all.

Very healthy :).

If you can plant it out, do so. That's where they want to be.

Your later pictures don't look much like your first picture. Whatever was causing the leaf curling seems to have gone away. Is there a problem anymore?

I too had the same problem last year when I started tomatoes under lights in my basement. The problem was temporary as they grew out of it in short order. I am not positive but I thought perhaps it was from too much fertilizer. I was feeding them with 1/2 strength Miracle Gro each time I watered them. Then I mixed up a gallon again but made the mistake of mixing full strenght. Since I water about twice a week when they are in my somewhat cold basement I assumed perhaps it was too much nitrogen causing the curling?

After that I stopped fertilizing with each application of water and the problem resolved as they pushed new and more normal looking growth.

It might be a variety telated issue. I say this because the one shown in the last picture looks normal to me. I have had varieties on the garden with leaf curl, while others next to them were normal. One of those was Black Kreme, as I recall.

Yes, so probably the one in the last picture is just this kind of variety.

Thanks to all.