I saw Alduin at the dragon mount which is just outside of Rorikstead. He was trying to resurrect the one who was resting there (Nahagliiv) but I disturbed it by hitting Alduin twice with dwarven bolts and he fled away. I walked on the mount and waited to see if he comes back but he didn't instead of it Nahagliiv said to me from his grave:
"Speak, if you have aught to say worth the listening."

What he means by that? I have tried a few shouts but they have did nothing. I wonder if there's something I can do with Nahagliiv now - is there a misc quest or a reward hidden there if I'll pick the right shout or is there something else? I'm curious to know the meaning of this whole thing.

Probably a glitch.