Although Pa Law generally requires a seller to fully disclose any known material defect by the seller to the buyer, there are many exceptions to this rule by which no disclose is required to be made.
You can see the Pennsylvania Real Estate Disclosure Staute here:
http://www.parealtor.org/content/AssetMgmt/Legal%20Services/Laws%20&%20Regulations/Dislcosure%20-%20Inspection.pdf
Some real estate sales/transfers that require no disclosure include:
-transfers pursuant to a court order
-transfers of a probabte court
-transfers made during a bankruptcy
-transfers made via eminent domain
-transfers resulting from a defaulted mortgage
-transfers to the beneficiary of a deed trust
-transfers during foreclosure
-transfers under the sale of a foreclosure
-transfers from one owner to another
-transfers where the owner has never occupied the property
Etc…
Yours may be a situation where no disclosure was required under State law.