What's pushing the US to apologize to Japan?

Anger Spreads Over Kevin Maher's Derogatory Comments on Okinawans
[link to peacephilosophy.blogspot.com]

Kevin Maher, ex-Director of the Office of Japan Affairs and former U.S. Consul-General of Okinawa was removed from his post on 10th March 2011 due to what he said in his lecture for the Uni students on 3 Dec 2010.

The reason of his removal was that not only Okinawans, Japanese government, but the US government also took his comments as derogatory to Okinawans (and Japanese in general), and the US made official apology to the Japanese government on 10th March 2011.

This swift move of the US to make an official apology to Japan was unprecedented.
It was a great surprise to the Japanese government, as this kind of cases were usually ignored by the US government.

Why the US is paying attention to such a small country where is bankrupting and seriously riddled with deflation, not really having anything to look forward to? (...Got plenty of earthquakes, and more than 50 nuclear-powered plants standing on top of the faults lines.)

The geophysical strategic value of Japan is there, in order to deal with China.
Certainly China has been gathering monumental military power on the sea in the Sea of Japan.
And the US circumstance has been changing a lot, so that also needs to be considered, too.

The US gets paid heck a lot to stay in Japan ("host nation support"), making it very easy for the US, so there's a good reason for the US to hold the presence in Japan with its existing economical difficulty.

But why the US government SUDDENLY changed its attitude?
Is it to do with Okinawa and its geophysical value?
Something urgent is happening in Okinawa region?...perhaps under the water...?

Okinawa is known to have massive stone structures under water.
May be trying to retain power over a grid there?

Who knows, but my speculation grows...