That is very interesting... I ran into a problem with my brother and 3 of his friends' return flight was messed up. Delta found me 4 low award flights from HKG-NRT-DTW-YYZ departing ~8 hours later (Nov 30).

Originally, they were suppose to leave via HKG-ICN-YYZ on KE, but they missed their flight. I called the premimum sales line and the SLC agent was wonderful in finding me the alternative leaving ~7 hours later. I was charged the $150/person change fee though... no additional taxes nor miles.