I am not sure, but suspect light burn if you know you had your lights too close. I recommend that you provide more information (lights, growing medium etc) so that others can better help you.
I also highly suggest checking out this thread to see if you can identify your problem: Plant Abuse Chart
damage of that sort and in that spot is hard to impossible to do on a young vegging plant other than by some sort of physical damage. It does not look like the normal presentation of any sort of excess or deficiency. I also strongly suspect light burn as being the cause.
It looks like u left water or fertilizer & water on leaves and it burned in spots where left wet and put under lights. The water acts as a magnifier on the leafs and under the light it burns. my 2 cents.