Deckard thinks he hears the question in that even if Kagerou doesn't quite voice it as one.  There's also the ninja-bot's body language.  He stands from his desk again, approaching –slowly, giving Kagerou more than enough time to register him doing so and react if he's going to –and lays a hand softly on his shoulder, trying to shift to catch the other's optics.

  "You're wondering why?"  He wasn't sure, but that seemed the most logical guess.  Even if he couldn't see how or why the other would even wonder that.