1.25 is fine. The funny thing is, I made a new account recently due to child account issues (after having my old account for 3-4 years) and after playing for a week or two my KD was at around 1.40, but then I had a party and let a few or my friends use my account(who are inexperienced in Halo, or FPS's at all, some of them) admittedly I did use my account quite a bit that night, but we were playing with the screen split into 4, so I probably got 4 times less kills, and 4 times more deaths. Splitscreen's a -blam!-. Plus, I was thrown off my game because of all the ruckus.
(I know, excuses, excuses, but these ones are valid)
TL;DR: My new accounts KD went from 1.48 - 1.08 during a party I threw.
[Edited on 03.09.2012 4:23 AM PST]