As with most seedlings that are at the cotyledon stage, it is over-watering that usually stalls growth. They are living off the seed coat still in the soil and when it is too wet the roots stunt and growth stops.

If you are comfortable working with them at this stage then you can transplant them into fresh growing mix (bury all that leggy stem) and it will usually kick-start a new growth spurt.

If you want to wait until they get true leaves, fine, but as they are slow growers anyway it will be awhile. Meantime, less water, more light, cool air temps.

Dave

Thanks. I noticed that the soil seemed kind of damp. I will water a lot less. I am scared to transplant them, but I am going to give them more light. I may be letting my own impatience work against me.