User blog comment:Menara/The Son of Sobek: The official PJ and Kane Chronicles Crossover/@comment-5593616-20130515180205/@comment-3146930-20130516235125

It isn't just that he mentions them, it is the fact that he instantly jumps to the conclusion that Carter is an escaped soul that used the Doors of Death. Thanatos was captured some time in October, meaning that escaped souls could have started appearing some time in the two months between Jason being taken and Percy being taken. However, when Jason, Piper, and Leo return from their quest to free Hera, everyone is shocked that the dead are rising again and monsters aren't staying dead. Even before that, Drew questions if the Great Prophecy has started, but doesn't list the dead rising from their graves as a sign of something happening; which you would think would be not worthy. No one even seems to know what the Doors of Death are until The Son of Neptune, which is when Percy first encounters an escaped soul.