Heh.
Sorry, I was a little vague in my wording there.
I meant that you probably have to start a new game (or load a savegame from before you completed the quest) and complete the quest again.

You could also try looking around in The Vault:
http://fallout.wikia.com/wiki/Fallout_WikiMaybe someone else has encountered this problem.
edit:
http://fallout.wikia.com/wiki/Death_From_AboveIt says here (under Bugs):
Quote
As of May 30, 2009, the achievement "Death From Above" and the 30 points are working on the 360.
So, if they patched a problem with the achievement, it might show as unachieved for you because you completed the quest before the patch. This could mean that the 30 points are a part of your total gamerscore, even though the achievement looks like it has not been achieved.
In any case, I would still recommend you try reloading an earlier save and completing it again, if you think it is worth the trouble.
This post was edited by PlanHex on Oct 24 2009 11:22am