A fewweeks ago I was ticketed SEA-PDX-EUG-SFO-PHX

I got to the airport early in SEA , not feeling well and then sent me SEA-SFO-PHX.

Two days later I was routed SEA-SFO-PHX and they sent me SEA-LAX-PHX. So I think the poster who said as long as origion and destination dont change its no problem was correct, never was "as one of our best customers" mentioned