Billboard, Ground Lease and Permit Ads

Hi Guys,
Ive noticed a significant pattern while reviewing the Billboards For Sale. Some of the Ground Leases/ Permits have not been revised since 2008. Does this mean that those locations or Billboards have not been sold, or is this just a case of lack of communication between the seller and Could the seller have sold the location and not informed the site? Curious to hear from you guys. Thanks