Is this not considered to be possession of stolen property? Yes, I think this crosses a line.
I recently purchased a Trivial Pursuit game from a secondhand store to add to my collection (I own 7 different versions). The box bulged at the top … it turns out that the reason for the bulge was 17 sealed envelopes from the Department of Education and various student loan lenders. Not only were these document not stolen, but the actual owner had SOLD them to me (by consigning them). Nonetheless, I didn't open them up to see if there was any valuable information inside (considering the age of the documents, I can guarantee that the guy's SSN is splashed all over the documents)