My strange meditation experience

I was meditating in a small canyon near my house when I decided to restart because the breathing pattern was wrong. I opened my eyes, but I decided to not move at all. So I spaced off into the distance because the area I was in was just nice to look at. Then the really strange and almost supernatural thing happened. I felt a force slowly pulling my head backwards. I decided to commit to it, and I gently layed on the ground. Now this force wasn't some weak force I could only feel a little bit. It was quite powerful and somewhat insistent that I lay back. This is definitely the strangest feeling I had while meditating (another strange one is when I felt like my arm was melting away from my body).