Sorry if this has been discussed thoroughly, but ive been hearing a lot of people saying they think Jacob jumped into Sayids dead body, but if that was the case then why would Jacobs note say that they would be in trouble if Sayid died? And so far the only one I have seen thats been able to appear as dead people is Mib. So im guessing Mib is "Sayid", thus the fact that the others might be in trouble. Perhaps he came from underneath the Temple to avoid the ash? Or parasite hitch hiked on Sayid as they were going to the Temple. And I know people will say but Mib is with Richard and Sun! But we have seen the smoke monster break off into three before, and based on the assumption that Christian is also Mib, we saw him with Claire, who seems to share the same fate. So we may have already seen him seperated into two "people". Thats just my opinion for the minute though.
And that might be why Miles had that reaction, whatever it meant.