Nate Silver, formerly of Daily Kos and now at the New York Times, tweets:
The numbers being floated about missing votes in Brookfield seem reasonable. Would be ~11% of Waukesha vote, same as in Prez election in 08.
Late on election night, the AP count showed a number of unreported precincts in Waukesha county. But when those precincts were added no new votes added to the tally. I'm not sure if that's related to the 14,000-vote correction today, but it seems like it might be. At the very least, it should be pretty easy to determine whether or not an entire city's votes were left out of the election night count.