There's no way those babies are rootbound in those pots. I've seen bigger plants in 16 oz cups. They are a bit shallow, so they are probably drying out fairly quickly. I wouldn't try transplanting until you get them out of stress.

I would guess underwatering is your problem as others have suggested. Be carefull not to over compenstae though. Just give them a good watering and then water them again when the top of the soil get's a little crusty.

Also, I would back those light off a bit until they perk up. They won't be able to utilize all of that light until they recover a bit anyway.