The first utterance out of a reporter's mouth when Bill Gates disclosed plans to ease out of day-to-day management at Microsoft was to question whether Gates was leaving the company earlier than expected. Microsoft officials should have been prepared for that, but they weren't. "I don't remember ever making a prediction about a particular timeframe," Gates replied. In fact, however, Gates did make such a prediction, in 2003, when he indicated he would keep working at Microsoft for another 10 years. That means he'll be exiting five years sooner than he said he would.The question came from The New York Times reporter John Markoff, the first person to speak up after Gates and Microsoft CEO Steve Ballmer surprised the world with news that Gates was on his way out. "Memories are a little vague, cause it was six years ago, but I seem to remember you guys saying that you had taken a gut check and decided to stick around for another decade," Markoff said during the Q&A that followed Gates' prepared remarks. "Am I wrong on that?" Markoff asked. "And has something changed if my memory was correct?"

According to a transcript of the press conference on Microsoft.com, Gates responded as follows: "I don't remember ever making a prediction about a particular timeframe....I don't think I ever made a statement that would particularly say what my career plan looked like."

Oh, but he did. Rewind to August 28, 2003. Gates is speaking at a lunch hosted by the Detroit Economic Club in Detroit. At the very end of a long speech, Microsoft's chairman and chief software architect closes with these remarks: "And it's very surprising to me to be able to say that the same kind of excitement I had when I started Microsoft at age 19, I have that today. Many people ask me why I don't retire and just focus on philanthropy, which I love doing a great deal, and the answer is that I want to take the half of the dream that we've realized today and make it in the rest of my career, which I have a little more than 10 years; make that full dream come true, and make all of these scenarios a reality for everyone here, and everyone around the world."

In that quote, Gates makes a distinction between his technology "career" and his philanthropic work, and he had a very specific timeframe in mind for the former-"a little more than 10 years." I remember his comment clearly because I blogged about it at the time. In an odd coincidence, Venus and Serena Williams had mentioned their own plans to continue in professional tennis for 10 years on the very same day that Gates made his statement in Detroit.

What this means is that Gates is cutting out five years earlier than he himself expected not that long ago. Obviously his plans changed. Markoff last week asked why, but didn't get an answer. We can only speculate that it's for the same reasons Gates and Ballmer gave last week: Gates wants to devote more time to solving the world's health and educational challenges, and other people at Microsoft are ready to step in for him.

My guess is that Gates is also getting burned out on solving one huge internal problem after another--gaping security holes, costly product delays, the shift to hosted software, the threat of Google, court battles--though I would never expect him or his inner circle to admit that. But the least they can do is acknowledge what Gates once said about his tenure at the company, and why he's changed his mind.