Distracted as he is, Dirk is paying an inadequate amount of attention to his surroundings in general--he still hasn't actually put down the plate he's holding, and for no better reason than he's forgotten he was holding it. So Steven's questionably-sourced pocket ghost? Whatever it's up to, it's so far evaded his notice.

Besides, the frames Dirk wears--sick as fuck though their look may be--are not exactly advantageously tinted for the detection of shadowy shapes.

"And now he has no more control over me than you did, reading it."