A reader corrects the record:
You've conflated the two Bushes here. The Japanese-American apology and restitution was the father (George H.W. Bush), in the late 1980s. The slavery apology was the son (W.), shortly after he left office.
Reagan signed the Civil Liberties Act of 1988 that apologized to Japanese Americans and provided financial restitution for their WWII-era imprisonment.
Another points to a timely Onion article posted last week: "Romney: 'We Should Never Apologize For American Values Or Japanese Internment Camps'. Another reader:
Another example of a Bush-Cheney administration apology that today's Republicans REALLY don't like to talk about is the April 2001 letter that ended the spy-plane standoff with China. The State Department went to great lengths to ensure Bush himself didn't have to sign this message and that the expressions of regret were limited to how the event ended rather than how it began (the US sending spy planes along China's coast). Nonetheless, phrases such as "very sorry" and "sincere regret" make it hard to claim that this letter wasn't an apology.