Google has enlarged their search box by giving it more height. The search box both on the Google.com home page and inside search results page is taller. It is a subtle change but clearly Google changed the size of the search box for a reason.
And on the home page, the search box is not just taller, it is also less wide.
I created an animated GIF of the before and after so you all can see the changes clearly.
Google Home Page Search Box:
Google Inside Search Results Search Box:
Again, this is a small, subtle change, but we like to document these.