Why am i indexed by google but not yahoo?

Hey everybody! Glad to have found a site like this with so many active members! Maybe someone can help me out with search engines?

I've been plugging away at my site for a few months now, and I've tried not to break any of google's seo rules about content (many of which I've found by browsing around here btw) and I'm listed in a few of other people's sites/blogs, and also a few seo-friendly internet directories.
Also, my site uses blogger.com's blogging software, but I host it on my own domain. Lastly, in each page's header I have the metatag for robots to index, follow.

Now, Google indexes me pretty good - i'd say they're maybe a week behind my daily updates.

But I'm not indexed very well by yahoo - they're like a month behind.

Why does yahoo hate me so?

Or is it b/c I need to be in existence for more than two months for them to crawl regularly?

Thanks all!