Lorel - 3:57 pm on May 9, 2013 (gmt 0)
Check your website for over optimization and your back links to see if you have repeated your main keywords too often in the anchor text/link (Google wants to see lots of variety in anchor text). If you have focused on one keyword/phrase too often (other than your business name/domain name, it may help if you get rid of some of them, especially if it's obvious they were paid for. Also check to see if any of the backlinks are from bad neighborhoods.
You said earlier:
Now this looks like a concern point. While developing a page i look out for three things: keyword in Title, keyword in URL, and keyword in page heading and in the first paragraph. Sometimes the page content is big or sometimes less based on the topic. Is this an over optimization.
If you take your main keywords for the page out of the title, etc., then it may harm your ranking.
Over-optimization occurs when you repeat your main keywords too often in the title, text, menu, etc. Just write it for people, not search engines. Ask yourself, "am I doing this so I'll rank better", and if so don't do it.