She sees very well indeed; Lan, who has spent a good deal of his life observing people, wouldn't have picked up on that fact so fast. He does notice her peering, but his assumption is that she knows what a Warder is. That's rare here, disconcertingly so, but perhaps she knows Kim or Behrooz, or one of the people from his world.

He inclines his head slightly.

"I am alone for the time being."

For the evening, most likely, unless Moiraine comes downstairs, but there's no particular reason to give unnecessary details.