Don't know if that is mixing metaphors.

I have launched two small new sites on the same hosting as my other sites and Google was very slow to find them.

Checking stats today I noticed the Google bot crawled all the web sites on the same day. Is this a usual phenomenon. I am wondering, because only one site has a forum and blog attached, will constant updates to these add ons result in frequent google crawling on all the site?. That is, if I make changes to the sites do I just update the blog as an invitation to crawl all the sites - or this another example of the free lunch that doesn't exist?

Just wondering if anyone else has experienced a similar regular response.