He's been for his swim and is just towelling himself off on the beach, too agitated today to sunbathe himself dry as he usually does, when the sound of someone running makes him turn.
Oh. He hasn't spoken to Kirk since waking up together after the whole twenty year debacle and then chucking him out of the apartment rather rapidly so he could call Ianto and ruin his relationship still further, so it's an unusually awkward-looking Jack Harkness who reluctantly acknowledges the other as he runs towards him.