<<The flap has a tear from top to bottom, big enough for the chip to escape from, then appears to be resealed>>

Did the seller comment on this. Did he reuse an old mailer. Obviously if its a new mailer, the chip was stolen in transit. Then again I also fault dealers that drop a chip "loose" in a mailer.

The sad part is, a loosely packed chip gives the impression that a coin were being shipped. I wouldn't doubt that once a chip was found, it was discarded as being worthless.