Wait a few days. Google goes through temporary glitches like this all the time. Back in January, I had many pages on a high traffic site suddenly tank in Google for about a week. I pulled my hair out every day trying to figure it out (and lost a lot of sleep over it), panicked and was just about to abandon ship and when all of a sudden my rankings were restored. Never did figure out what happened.
Ya, Exactly the same happened to me.It is now available in google.Couldnot figure out the problem though.
sometimes the google webmaster tool is not so fast to get the latest result, you probably excluded from the index some how, but it's not yet show in the webmaster tool page
had same problem but got listed afterwards again...... best of luck 2 u