That has happened to me before, exactly the same tone although I had the sensation of running in a desert before awaking on the floor.
From your mention of the bathroom floor, I can only assume you were urinating while standing, which is a very common trigger for http://en.wikipedia.org/wiki/Vasovagal_response. For more specific definition see: http://en.wikipedia.org/wiki/Micturition_syncope
Not a big deal really, but as always might want to get it checked out to rule out more serious conditions.