Two matters registered with an almost alarmingly similar level of surprise. Firstly, that Albus could not recall the last time he'd been called out on his manners-- and secondly that both he and Gellert, it seemed, had been collected and interned against their wills. Never mind that the back of his mind felt as if it was erupting with appraisals over the best course of action, the fact that Gellert did not know him proving to be a routine stumbling block for his thoughts. The implications, the possibilities--
No, he needed to think. He needed time. Alone.
Albus's demeanor changed entirely. He withdrew a little, conceding a more appropriate degree of personal space. His features were meticulously smoothed into the familiar composition of a politely neutral expression. Even if it was, perhaps, a little more distant that it usually was. Time, he hoped, he could buy. It seemed like an overwhelming shortcoming to not have considered such a scenario before; he'd turned out in his mind, countless times, the possibility of facing Gellert again, but never like this. The possible salve to his mind, that such circumstances were so infinitesimally small, was utterly useless. It had come to pass, so there should have been some way for him to anticipate it. In other matters, his concern was not so great, but there seemed to be an exaggerated sense of risk in being unable to predict events to which Gellert was tied.
"Forgive me," Albus said immediately, reflexively, his voice softening along with the focus of his eyes. "I thought that you were... someone else." And while it might have been a lie, Albus meant it entirely. He could not manage to amend the Gellert before him with the Gellert who left Godric's Hollow. Not entirely. But there was time for one last consideration, on last little bid. His eyes returning to Gellert's, their inspection far more veiled, he said, "My name is Albus Dumbledore."