Lol try adding more content to your index page. Just some images wont even give search engines a hint of what your site is trying to do. Maybe i can help your seo a bit. Shoot me a pm if you need help.
There is a need to build momentum in a website. One can be no. 1 in Google in one day, and no. 10 in the next day. Google's algorithm is being changed almost every other week. Congrats, though.
yeah... Google algor change always... need to improve for good unique visitors and better rank looking good...