Hi Steve,
I have the same thing happen to me. The explanation that I've read given in a couple of obe books was as you stated, that there was a separation while dozing off and then a falling sensation upon the non-physical reentry.
Very best,
Just curious about something. In the mornings and sometimes when I really physically tired and just dozing off, I awaken to feel unstead as if I'm about to lose my balance. As if I'm falling. Is this my astral body re-entering my body. I have never really been aware of being out of my body before...only these times where I feel like I'm coming back in. Any comments would be appreciated.