I haven't seen sprouts, but the first batch of great northern beans I cooked I threw out. At the time I was working and cooked them one night and started to finish them the next night and noticed all these little things floating on top. I thought I had got some bad ones (it looked a bit like worms). I told my mom and she laughed. She said they were the "eyes" of the beans and that they separate when cooked. I don't know if that could be what you mentioned or not.