The riddle isn’t really what the technical reason for the faster playback is, but rather why they haven’t converted the film to PAL properly. Most dvd’s here are at the correct speed. And I have never before seen a Star Wars DVD with this issue. It gives the film an artificial look, and makes it feel unnaturally rushed. It disrupts the whole rhythm of the film.
Yeah as Mavimao says above, you’ve just never noticed it before.
All my PAL Star Wars DVDs (and VHS tapes when I had them) are sped up 4%, with higher pitched audio. To be honest it wasn’t something I ever noticed until I started switching over to Blu-Rays, now I don’t really enjoy it. Probably for a lot of European people who are in their thirties now, 1997 was the first time they’d ever heard/seen SW played at the correct speed.