Oh boy. I used to work at UPS and the stories I could tell you... By the way, the reason sometimes you will ship a package overnight from say Illinois to Indiana and it winds up in California, is because usually all the priority packages go into the same truck (huge semi, not the little brown ones) to be sent to (usually) Louisville, KY if you are east of the Mississippi. Packages from allll over the country and the world are in these trucks together. Then they are unloaded in Louisville and sent back out to it's intended destination VIA airplane. Well when they are unloaded, if some mary jane smoking crack staff employee of UPS decides to chuck your package into the CA air container instead of the truck intended for the state right above the state they are in (which they can be right next to each other), well your package is CA bound. That is how a missort happens my friends.
Oh, and i don't know what exception means.