If it's too hot or too cold it will shock the plant causing growth to slow considerably, probably what's happening.
Peppers are warm season crops that grow best at temperatures of 20-27C during the day and 15-20C during the night.
:welcome: from Australia.
Nice healthy looking plants, surprised to see the Thai Dragon budding already!
Good luck and may the chilli gods be with you!
Yeah I agree, hold off from potting up until they are well established, also generic potting mixes generally don't have a great source of NPK so you might want to feed your babies a weak solution of liquid ferts once a fortnight.
Also looking for Scorpion BT seeds, don't have a great deal to trade;
Bhut Jolokia - Red
Trinidad 7 Pot
Peter Pepper Yellow
Black Pearl
if anyone can help thanx!