A complex mechanical device is supposed to be an assembly of smaller parts. The bigger the number of parts, the bigger the possibility that the assembly of them become loose. Especially if these parts are always subject to vibrations, torsions and shocks. Nothing strange in this.
Due to the complex fitting and interaction between parts it is very difficult, if not impossible, to find the root cause of some subtle rattlings. I remember, on my old BMW Z4 E89, a squeaky rear suspension assembly that the dealer never resolved. The noise was also related to the outside temperature: more noise in winter, less in summer.
Yes, because to the variables you have to add also the natural stretching of the materials depending from temperature (Concorde used to became longer of several centimeters when heated by air friction at supersonic speeds).
Believe me, you could have major rattles fixed if there is a loose connector or something similar, but I experienced that sometimes removing a door panel and refitting it could generate new random rattles! It is always a trade off.