He's thinking about legacy building at this point and the one thing he doesn't want to do is leave at the top of an immense bubble and have it burst soon after he leaves. He kind of touched on it yesterday in relation to the housing market.
What stock investors probably need to be thinking about now is 'what are profit margins doing?'. A little inflation wouldn't be so bad for the stock market, for Corporate America, but it wouldn't be good for the economy or the consumer.