He might not have wanted to startle Dairine, but she was pretty concentrated on what she was doing. So when she feels the hand touch her shoulder, Dair jolts, taking her hand off the train as she gets ready to fight.

Her reaction is short lived once she sees what he is doing. With only a brief sour look, she places her hand back on the train's engine.

"Coulda warned me first," she mutters quietly under her breath.