When designing PCBs, and especially when creating your own footprints, a crucial stage of the QA process is laying out your devices & ICs on a printout of your board.
Had I done this, I would have avoided the width error made in the footprint for the flash IC. While the error is not fayal, as the chip still makes good contact further up the gull wings, it is not within spec and could fail entirely under certain conditions.
However, it is not always possible. In my case I did not yet have the chip prior to sending the board design to Shenzhen. Remember to triple check any custom devices/footprints in your PCB CAD software of choice.