Check the doors and windows to see if they still have the right gap all the way around and if they open and close properly.
If they aren't out of square and nothing showing on the outside or the basement/foundation wall, then it may not be any major shifting which could be expensive to fix and/or adjust for. It would probably be the walls and ceiling flexing or minor settling and drywall problems happen.
Load bearing walls in the basement and on each floor usually support house weight and are around the outside and also run down the middle of the house.
Many times around doors in nonload bearing walls, they don't put in much of a header above it which helps it flex more.