I was very happy when I noticed that on my Blu-Rays. I get what they were trying to do, make Yoda look forty years younger, but they only succeeded in making him not look like Yoda.
Besides, if your race can live to be 900 years old, is 40 years really going to make a significant change to your appearance?
And let's be honest here. While we dislike edits to the OT because it was done right the first time, the prequels need as much improvement as they can get!