That sucks, but at least they have you all together still - there are some threads on here of people getting re-assigned seats away from their children (and they complain for some reason and such.

I had a similar thing happen, but it was a much more painful experience - recent YYZ-HKG, flight time changed by 4 minutes, so they kicked myself (SE) and wife out of 18AC on the 77L (only pair of seats - all others are 3 together) which we had booked 300+ days out, and put us somewhere near the back. I checked 4 months out, all was good. I checked 10 days before and found this mess... annoying, but the said their was nothing they could do.