I finally managed to get all my contacts good, so the "horseshoe" disappeared and I was confident I was getting good data, for a full 20 minutes! The start of this graph I was getting settled, but I'm pleased to see the alpha predominated while I was listening to my meditation and for a few minutes afterwards while I practiced on my own.
Is it odd that theta and delta were above gamma? Or is that just because my mind is all unsettled today? I didn't sleep well last night and I wondered if I might fall asleep during meditation. It will be interesting to see the brainwaves when that happens.