another +1 for cmpman. Turn that heat mat OFF as soon as most of your babies have popped through the soil line. The heat is only to get them to pop. Or if you want, set it on a timer and set the heat to around 70 degrees but so that it shuts off at night and cools down.
The 80-85 degrees typically used to germinate is most unhelpful once germination has occurred. It makes them grow too fast. What you want is slow, thick, chunky growth at the correct pace.