Meta description question

So when Google cached my site they used the first few lines of content from my mainpage as the website description instead of the meta description tags I set up for it...anybody know why that may be? Thanks a bunch.

is your page dealing with iframes? thats only reason i can think of for doing so. Also maybe look at the cache age of the page. As google might have cached the page before you added meta desc tags into it. Either way though, next time google crawls your site and reindex's your page, it should only take the meta desc tags.

So Google generally uses your first few lines of content?? Or do they switch it up??