The only thing you can do at this point is fire up that light in the closet for at least a few hours and check the temp with a good thermometer. As long as the closet doesn't get hotter than about 80 degrees, you're fine(ideal temp is 70-80). You'll have to figure out how much to ventilate by opening the door, again, only one way to tell for sure. If your closet is running temps greater than 85, you need to figure out a more agressive plan. Understand that nearly all growth ceases at about 90 degrees.