Not sure if there's a problem with my Burpee Big Mamma's

[gundogblue]

I put in three variety's of paste tomatoes, San Marzano, Amish Paste, and Burpee Big Momma's. I planted the Big Mommas about 2 weeks ago, and they are growing well, but the leaves on them seem to be curling, or folding in half. There are no spots on them, and I looked for insects, and found none. I've been watering them in late evening and every other day with a watering can, I give each plant about a 30 second count with the water can, and they're mulched I stuck my finger in the ground near the plant, and it's not dry, or overly wet either, my finger comes up damp and black from the dirt. Could this be under or over watering? All the other tomato plants are doing fine with no leaf curling, could this be a trait specific to these tomato plants? Any advice on this will be appreciated.
Thanks,
Paul

[rainbowgardener]

If the leafs curl upwards and tend to get kind of thickened, that's called physiological leaf roll. It is a protective mechanism the plant has under stress, e.g. from cool rainy weather, severe pruning, going back and forth between very wet and very dry.