I guess this may due to the reason that your site has been created in flash. Since google cannot crawl flash sites, it may have shown the thumbnail image.
It also shows the first thumbnail from my flash gallery which is presented on part of homepage (linked from signature). My site is definitely not a flash based site…
Who said that Google can’t crawl a flash based website
Google can crawl a flash based website with as ease as any other site
except the fact that it won’t be able to read the text & description inside those flash things.
Google’s crawler is very powerful & i have seen it crawling .html, .php, .docx, .xls, .txt etc… just to name a few here