Is this anything I should worry about?

[nyuldaniel]

My seedlings are going great, just noticed a few have upward curling leaves and some mold on the soil. Should I take any actions? They are in a mild soil for seedlings, I added a couple fertilizing pellets 2 days ago (leaves were already curling before that). I only watered them once since transplanting them, approximately 4 days ago. 

 

[EvanWilliams1988]

Let your soil dry out a bit. Looks like over watering. Do you have a rotating fan?

 

[rjacobs]

yup, stop watering them for a while.
 
Your first pic, the cotyledon leaves look like them have edema which is caused by over watering.
 
My seedlings are about on the same schedule as my big plants, right at 2 weeks between watering.  My 4 biggest seedlings(out of about 30 right now) were showing signs last night of needing water(which puts them on about day 12 of 14).

 

[nyuldaniel]

Thanks for the replies! I have a small heater running in the room almost full time, but maybe I'll add another fan. Crazy how easy it is to over-water them, I only watered once, when the top layer of the soil was bone-dry. The cups even have a layer of small rocks in the bottom for better drainage.

 

[Lovepeppers]

Personally I wouldn't add rocks to the bottom of your pots. You inhibit growing space. Just add a bunch of perlite in your potting soil, for great drainage. Wait till most of your water is evaporated before watering.
Next time you fill a pot with soil, feel how heavy your pot is. Then water. When your curious when to water, pick your pot up and feel the weight.
Don't go by how the top may look.

Happy growing!!