Esbern, Delphine and I were on the way to Skyhaven temple when we ran across Alduin ressurecting Nahagliiv west of Rorikstead. I didn't think Esbern would recognize Alduin or have any special comments, and he didn't. But shouldn't the story writers taken this possibility into account? Not even Delphine, who has seen Alduin before, made any note of meeting Alduin again. In fact, she tried to shoot him with some arrows, at which point Alduin turned around and used a UF shout on her for her cheek.
Interestingly, after we killed Nahagliiv, Esbern comments: "Alduin can't ignore this for long." Yeah, Esbern, I agree, considering HE WAS JUST HERE!