I recall reading that in the early in the 737 (BBJ
) winglet program that the center of lift on the wing moved forward a small %. Now that caused the Trim characteristics to change, in this case it made the 737 tend to over trim.
If an aircrafts center of lift moved aft then it would tend to under trim.
The 737s was having this issue at cruise and the autopilot was updated with a the changes.
A 757 in a landing configuration is very different from a 737 in cruise, but the principal of center of lift would basically be the same. A trim issue would certainly show up with the autopilot in an autoland mode, as most of the flight down the glideslope is done with trim, with the flare being done with elevator input.