No worries... just let it do its thing. The plant is going to want to survive, I dont think the roots will even want to be out of the soil. I have had roots peek out but then quickly retreat and/or shrivle up.
my plant is 12-14" tall, how far long i dont under stand but there under 105 watt cfl's intill they go into 2 flower under 600Watt hps, so not much heat on the few roots poking out, not 2 worry?