Although Bran caught a brief glimpse of Jon in season four, Jon hasn't actually laid eyes on his younger brother since way back in season one, when he first departed Winterfell for Castle Black. No wonder Jon is emotional when he spots Bran upon arriving back home, throwing his arms around his brother and planting a relieved kiss on his forehead, as he tearily observes, "Look at you, you're a man!"
Unfortunately, Bran's detached serenity undercuts the emotional resonance of the scene. "Almost," he replies, offering his brother a vague half-smile that wipes the joy from Jon's eyes, replacing it with sad confusion. While we knew that his first meeting with the Three-Eyed Raven was bound to be unsettling for Jon, it was still disappointing to see Bran give him such a tepid reception after such a long time apart.