This expiration date on paper must be something new. I had purchased a couple boxes of Portriga Rapid a couple of years ago which was developing black, not just fogged. It must have been stored improperly. I contacted B&H and they wouldn't take it back but refered me to Agfa.
When I asked Agfa about expiration dates on paper they told me paper really doesn't expire as long as it develops and base fog is low. The paper's emulsion may get slower or more contrasty with time. Agfa told me they can trace the expiration dates by batch numbers coded on the label which will give them an idea when it was made.
My paper turned out to be 5 years old and was also discontinued 2 years prior without anouncing it to the public. Agfa is such a great company they took all the paper I had, pre paid FED-X pickup and replaced it with brand new, fresh paper of MY choice. They recomended their Record Rapid as a comparable replacement since the emulsion was similar if not the same.