Let me explain myself a bit more: The impression I got from contacting schools after I got the NSF was that in general they had high yield this year, so they took fewer NSF winners than they had in the past. Basically, my timing was off: I might have gotten in if I were in the first-round pool, but since so many people had accepted offers already, they gave out very few second-round offers to people like me. So I think I would have a good chance next year.
Now, I have a few reasons why I'm nervous about sticking with the offer I have. I don't like the location; it's cold and depressing. The faculty strengths are fairly narrowly specialized in areas which I'm not entirely sure I want to be in. But I don't dislike the place. If I hadn't gotten this NSF thing, then I would be satisfied with going there. But now I'm afraid I'm going to waste this very rare opportunity I've been given to make the most of my career.
I do think that there is a sort of glass ceiling in the profession if you come from outside of the top 5. If you look at the faculty in the top 5, the vast majority had PhDs in the top 5. At the very least, a PhD from a top program has a high signaling effect on the marginal that is hard to measure but might be worth waiting a year to reapply. Certainly if I don't end up becoming a professor, the signalling of a top 5 name will be even more important. Or?