It is called "tomato leaf roll" and you can Google that term for lots of details. It is primarily caused by inconsistent soil moisture levels and as plants outgrow their pots it gets more and more difficult to stabilize the soil moisture.

Dave

It means your plant is stressed in some sort of way. Try to figure out why. As Dave says, a lot of the times it is caused by irrigation issues, but not always.

I agree with Dave and NC.

It is a manifestation of some kind of stress. I think over watering is more of a suspect than under watering.

Then there is a varietal connection ; that is some varieties are prone to leaf rolling. Three years ago I had a Black Krime. It had this issue, while the other varieties next to it were fine.

Sey

Thank you all. I will try changing them to a bigger pot