Thank you. I'm still confused, though, because I started out at 0 karma for the month, making the changes in the numbers non-equal. I'm now on {16, 2}, which is consistent with {12,-2}, though.
Remember that the change in karma-for-the-month is the sum of two things: changes now and changes a month ago. So it can jump down even when nothing interesting just happened, if you got a bunch of upvotes 30 days ago.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.