i have encountered those brown spots before and it is a lack of some type of nutrient probly nitrogen... i've noticed that your plant didn't get long and stringy which means that the light was at a good spot... if its too far away the plant will start to "stretch" towards it.. a good way to tell if its too close is by putting the back of your hand under the bulb, if your hand is too hot for comfort then its too hot for your plant