I had dreamed the scene about three weeks ago. I remember waking up from the dream (in my new room at my new place) and being annoyed that I had been dreaming about work - I spend enough time there already, damn it. Then I thought about it a bit, amused at how the guy I had been talking to in the dream was unknown to me, but oddly familiar. I wrote that down to the (il)logic of dreams, thought to myself "I'm such a geek that I dream about printer configurations, no less!" and went on with my day.
The equations don't care if they run forward or backward, indeed.