Well, because I have been lurking charts for 3 years and I've never seen it. Lol. It's not impossible, no, but the temp shift is not that convincing to me.
But it's possible. Saying "CD9 is just unlikely in itself" sort of sounds like you talking out of your ass, and it sounds negative. On a cursory glance there are hundreds of charts of FF with O taking place between CD 8 and 10 (and that's just the sample size I used). OP already said she used OPKs (in her OP).
I'm really not trying to harp on you, but there have been a lot of people just talking out of their asses for the sake of participating without grounding their advice in much fact lately.