Nope, the 2004 First Aid is 496 pages. And the 2002 edition is 498 pages. So, basically, the overall length of First Aid hasn't changed at all. But, if you compare the section that everyone probably cares the most about - Database of High Yield Facts - there is a difference of about 20 extra pages in favor of the 2004 edition compared to the 2002 edition.
The fact that they have expanded this section by less than 10% in 3 years is a good thing, in my opinion. It means they are being super selective about the information they are adding. Some review books go bat crazy with new editions.
High Yield Embryology is a case in point. First edition was 47 pages. Second edition, the one that most people read now, is 151 pages. The book tripled between editions! Pretty ridiculous, if you ask me, for a subject that most people say they only got 4 or 5 questions on at the most.