^ ideally, you should re-track the car after having replaced any major components as it'll likely have disturbed the alignment of everything else (even if you've replaced like for like).
everything flexes anyway; if you put a car up on a full chassis alignment ramp, you can push the various components by hand (the movement is obviously in the rubber bushes) and vary the readings quite a bit - so these things are constantly changing as the car is being driven anyway.