Snap that leaf off at the stalk, and don't worry about it. Bottom leaves often do that, and they don't seem to need a reason.

Probably abiotic. Don't fertilize or provide too water. Time will reveal any limitations.

I transferred it to ground and it's doing gr8!! Thanks

How frequently should I water? The temps r in 80s with no rain and around 6-7 hrs of sun .

Yes, it depends on your soil consistency, frequency and method of watering. It is important that the water reaches a foot down into the soil to encourage root development, but not so much that the roots suffocate.

Watch to see if the plants are perky in the morning... If they are still droopy, they didn't get nearly enough water the day before.