Why is American Airlines’ computer pickin’ on me?

I’m fussy about where I sit on an airplane. There’s good reason for some of it and no sense whatsoever for the rest.
For instance, I always opt for a window seat. Yes, that means I have to climb over people if I have to make a trip to the lavatory during the flight. I don’t care. I want to be by the window. If I can’t see out, I feel claustrophobic, especially as I feel the plane starting to descend. I need to maintain visual contact with terra firma.

I have a trip to Washington, DC, coming up in April. Most of my travel on the U.S. mainland will be on Amtrak, of course, but I will be flying from Maui to Los Angeles, from there to Chicago, and finally back to Maui from Los Angeles. Many weeks ago, first checking with Seat Guru, I selected my seats on those three flights using the American Airlines web site.
Today I was double-checking details of that trip. That included going to American’s web site and calling up my itinerary, which is when I noticed that I was assigned to seat 14A on all three flights. That didn’t seem right, so I checked the email confirmation I had received from American when I originally booked the flights. 
The seat numbers were all different. Without so much as a by-your-leave, my seat assignment had been changed on all three flights.

Back to Seat Guru I went to check on seat 14A and – Horrors! – that seat had no window on the Boeing 757, the plane I’ll have for both of my trans-Pacific flights. Same thing with the 737 I’ll be taking from Los Angeles to Chicago: no window!
While on the American Airline’s web site, I re-assigned myself back to my original seats. And I’m going to check every few days to make sure that this time, I keep them.
No wonder more and more people hate to fly. And no wonder Amtrak is setting new ridership records year after year. For one thing, there’s a nice big window at every seat!