Statement by Lucasfilm from theforce.net:
"We are always impressed with how closely fans listen to the many different sound mixes we have made for the Star Wars movies over the years. It is flattering to know that, indeed, the audience is listening. Consequently, each mix comes out differently and any changes that you hear on the all-new Dolby Digital 5.1 Surround EX tracks on the Star Wars Trilogy DVD set are deliberate creative decisions. We can confirm that there are no technical glitches as has been reported."