This isn't surprising. As someone who has been hypnotized, once for a past life regression at a psychic fair, and a number of times by friends when we were experimenting with it, I can say you can go into a different mindset or "feel", and I presume altered state of consciousness. Since that would change theta or alpha waves or whatever, I can definitely see this being detectable. It was interesting, exactly what it was that was determined, that it was more of a suggestible state, aware but cooperative and "open".