I am facing a strange problem with one of my new sites. Well not really new but its around 3-4 months old. Once I add a new post and use Fetch as google, its gets indexed right away. However after few days, it just simple disappear from the serps. However the posts are still present in Google cache. If I try to use Fetch as google again, it comes back to SERP. Then same things happen again (disappearing..) Any idea what's going on?