Rudder trim on climb then nulled then trimmed the other way on descent.
This phenomenon happens on the 767-300 regularly. I think you are allowed up to 2 units trim before we engineering types have to look at it.
The reason givin to me was due to different expansion rates of the fuselage versus the rudder cables. I know there are cable tensioners/compensators in these cable system but that is what I was told..
Another thing we regularly find is when a trim defect comes in. 744 or 763 The trim position indicator is a ribbon with an ^ on it. Most often the ribbon has stretched and no longer reads 0 trim when the rudder is centered and the EICAS position indication isn't fine enough to show up the fault to tech crew.
I have seen tech log write ups where crew have chased this trim indication error with aileron trim and had the A/C crossed up.