Has anyone had this happen to your client's site?

Not sure if is the correct forum to post this but I have developed and ranked several personal and local business web sites and this is the 1st time I've had this happen.

I just completed a local client's site approx. 3 weeks ago, uploaded it, submitted the xml sitemap to Google's webmaster tools and installed a server side visitor tracking software.

After about a week or so 9 out of the 10 pages got indexed by Google. They showed up when typing: site:www.mysite.com into Google search. I kept checking the rankings of the individual pages but they never showed up even with a couple of pages having a very longtail keyword. Usually pages end up getting ranked on pages 3 and 4 right after they get indexed but not this time.

So I just checked to see if the 10th page has gotten indexed and so I typed: site:www.mysite.com into Google and now nothing shows up even though in Webmaster tools it still shows 9 pages indexed.

I have done zero backlinking and I haven't received any kind of negative email or notice from Google. I have never experienced pages just disappearing from the index like this before.