I don't know, if this would be possible (at least for next time)? I mean, probably a lot of people don't read the blog (or even meta). These banners are displayed for so many things, so - why not?
I put up a banner here on Meta to try and explain the reputation situation. I figure that if they're already here on Meta, they're here to complain, so the banner should save everyone some time and frustration.
I understand the theory, but I am not sure this is a good idea, and I have opted not to do it.
That's because we'd be inviting every user in the system to complain about rep changes, instead of that subset of users who actually care about their rep scores.
EDIT: However, it IS a good idea to do it on Meta! I totally support that, so good job whichever mod just put in the banner here... (smacks self for not thinking of this)