Get a second opinion. Speak to an attorney. The disclosure laws here are a mystery to me, but if that guy only lived there for 5 to 6 years, they may have known more than they let you know. If there is a possibility of getting help with the problem, it's worth looking into. Definitely speak to an attorney now. If you wait a year to find out if it's still settling, you may pass a statute of limitations of time to file a claim. $30,000.00 is too much to spend without making some noise.
Tom in KY, let us know how it turns out.