A Puzzlement

The final numbers are in. Over at Mystery Pollster, with all the counting done, Bush got a bit over 62 million votes, Kerry a bit over 59 million, and about 1.2 million for everyone else.

Two months ago, it looked like Bush won by 3.5 million votes, with a 3% lead. Now it's been knocked down to 3 million votes and a 2.5% lead. I recall four years ago all the post-election counting extended Gore's lead by a few extra hundred thousand.

So I have to ask, is there a reason the final counts favor Democrats by a fair amount more than the initial counts? Is this a rule, or a fluke? Any ideas?