Google has been making changes.
More and more, they are tending to show a wider variety of results.
It’s all about ensuring they hit what you are looking for – even when your search may mean several things.
If you are searching for “mister” are you looking for a male person, or for a device for spraying little droplets of water?
If you search for plumber, are you looking for a plumber in your local area (probably), or maybe you just want to know more about the profession?
Are you looking for a web page, video or images? Information? A site where you can buy something online?
One way Google has dealt with this: It has been a firm rule for about a year, they will not serve up more than two pages from the same website.
That way there are eight other chances (not counting Places and Sponsored listings) to hit a home run with the searcher.
You see this where the second listing is indented slightly indicating it is another page from the same domain. Usually one is the home page.
Now Google has announced another tweak. Under certain circumstances, they will again show more than two pages for a domain.

For queries that indicate a strong user interest in a particular domain, like [exhibitions at amnh], we’ll now show more results from the relevant site:

Note that in the example given, they still show only 7 results from the amnh.org website. This puts three other listings on the first page of results. Google still hedges their bets.
Smart. Very smart.