System just works on segments and subsequent impacts - not earlier - if your first segment had cancelled/postponed - it would have changed whole trip (i'm sure routing would have stayed same)... its just the coded logic.. hence the human touch is valuable!!
I had earlier in summer SAN-DFW-IAH.. SAN-DFW late so it pushed DFW-IAH to next morning.. called EXP and since I had a IAH-ORD for next evening.. they were able to just get me SAN-ORD that night as I wanted after delay..