3 Week Seedling Flowered Why? No Pics

This happened to me about 2 weeks ago before putting my girls outdoors,Has anyone had a young seedling flower before when only 3 weeks old,wardrobe box was efficient,running floro in light tight box with correct everything to my standards,18/6 light on/off,growing in seed starter mix{all available except miracle grow and dont like nute burn} ,I about freaked when I checked my 45 seedlings when I noticed like 6-8 balls a hangin [I whacked it out}the other 30 females and 14 regs were fine, in all my years I've never seen this so what might have caused this so I can avoid in future,must be kinda rare unless intentional flowering is being done,thanks in advance