The answer, as he would learn in later years, is that Erika had been here. That's why.

It should not have been possible for Erika to walk through the area without stepping on anything, but somehow she managed.

"It can't be helped: I was working, after all." She pulled the tape measure ribbon off her table as she passed and draped it over her neck. Erika made it across the room, and took the outfit that was hanging there.