I've only so far added 5 or so nodes to my site. I've noticed that not all nodes are coming up in the search results. What I mean is searching for their title doesn't find them :S It works for some but not others. Why would this be the case>
3 Answers
The search table is created on cron job. So the sites that are added before the cron job would be displayed. Could you try running the cron and then try to do the search.
The problem as mentioned by the other answers is that the search table is only updated incrementally on cron runs as new nodes are added.
It's possible for nodes to be added faster than your current site is configured to process them on busy sites but you won't hit this problem with just 5 nodes :)
If you tell your site to re-index the content as proposed by indrock this will make your index reach 100% slower as it will start over from the beginning.
Drush actually provides functionality to force the site to finish indexing the remainder of content on demand. The command is:
$ drush search-index
Personally I've found that changing your search settings to index fewer items of content far more frequently (like 10 items per cron with a search cron task every minute) is better than larger, infrequent spikes (like 500 items once a day).
Your site is probably not indexed 100%. You can re-index the site by visiting admin/config/search/settings and clicking re-index.
This will re-index your site on cron run and you will be able to search the content.