I've felt it on and off for years; I used to think it was one particularly ribald young lass who, in the morning as she sat on the edge of my bed, I could feel HER arm vibrating. We talked about it, she felt it too but though it it was me....
Recently, I've woke to the bed vibrating. At first, I thought it was my Infratonic (great little gadget, google and buy), but the times I've felt the vibe, the Infratonic was on the nightstand turned off.
Furthermore, I have a semi-waveless waterbed. IT continued to vibrate for many seconds, I suppose from me. I've checked the bed and components, the floors, the house, its not coming from outside of the bed...it's me.
I've also felt it on my standard mattress, so I know it's not the bed(s).
Thanks to all for making me feel a little less nuts.