JohnB,
Looking at your pictures makes me think that when you planted your seeds that you raked the leaves back and just dropped the seed. After that, you may have walked over them to make contact with the soil. I am a little skeptical about planting seeds like that on any type of terrain that has any slope at all. Even planting them after working the soil a little and covering them, followed by walking the seed down to tamp them into the soil can allow seed to float to the top in real hard rain events. They will then migrate downslope to a point where they are stopped by roots or some obstacle.
I would suggest going back over your plantings and covering the plants gently with some dirt and leaves. Those rhizome tops are a good snack for any critter coming along. Here is what some of mine looked like that I planted on a slope this winter.