Am thinking about reducing the edit window.
I think that's a good idea, and I'll suggest 30 minutes.
I often edit with no notation because the edit is strictly grammatical or because I've used a better word...because of neurosis, to be precise, but if I change the response itself, I always check the "Edited" box.
A shorter window would do wonders for my neurosis as well as force updated posts should they be necessary after that long a period.