I think you definitely were seeing HI. I just recently discovered what it was myself though. I don't think you were in SP. You were just really relaxed and didn't feel like moving. SP (from what I've read, not from experience), is more like physically not being able to move even if you wanted to. Think of all the stories about people seeing demons standing above them and trying to move and not being able.

So, my opinion is there was HI, but not SP.