It sounds to me like you're right. I imagine the sensation you felt while in your dream was your physical body, and you probably felt both because you just entered the dream or because you were thinking about it.

The only other thing I could think of was that, because you were /thinking/ about feeling your real body or the sensation of laying down, you felt it. And maybe because you expected yourself to 'switch' consciousnesses like you experienced, you did. This has happened to me before in the sense that in a non-lucid dream, I pondered what it would be like to see myself in 3rd person, and then I saw it at the same time as I was seeing my own first person perspective. it was very strange.

Anyway good luck with your dreams and such! Hopefully this was helpful