Google rebuilt rank of websites, so your website rank can be change in this period. This called google dancing.

Googlre dancing is the period of time when google may decrease or increase any websites page ranking.

Google Dance is an out-dated slang term used to describe the period of time in which Google used to rebuild its rankings, and as a result of this rebuilding, rankings of Web sites on Google's SERP may fluctuate in order during a several day period.