Does Google Dances?? Just joking:p I guess it should be the changes in Algorithm that occurs time to time!!

Google Dancing is entirely different from Google Algorithm changes. Most people confuses them. Google Dance will just temporary and you will see only slight changes in ranking. May be because of that keyword trend.

Google dance is when a website fluctuates in rankings. Let's say a page ranks 3 and then changes to 2 and then goes back to 3 again. This "dance" was said to be due to the new updates on Google's search engine.