this happen three time to 3 sites. when i start to seo a site, maybe in a month or 2month, there is a time a page by seo(even other page) got boost for allmost keywords(from 100 to 30 or,400 to 90, or 30 to 7) , i think it is because google recognise site and give it trust. i have no build link for almost 1 month, and rank is stable. it definely is not reason link build or competitor thing. anyone got this too?