Medical marijuana growing?

I'm a beginner at growing cannabis. I started by germinating two seeds that come from potent strains. One that was so dark green it was almost black and the other was light green. The lighter shaded seed never germinated but the dark green one sprouted a small root hair in less than 36 hours. I let it germinate for two more days. The root hair became as long as the seed and I was eager to plant it. I put it in a plastic cup about 1/8th inch deep, root hair face down, and packed it gently. The next morning I went to check on my seedling and found that the cup had been knocked over and the seedling luckily was still intact, and the root hair had grown, not much, but it was noticeable. I replanted it. Now just this morning I checked on it again and it was knocked over, AGAIN. This time, the root hair had no noticeable growth. Is this normal?