Dell T610 on boot: "Invalid PCIe card found in Internal Storage slot. System halted"

We just shipped a Dell tower server on a pallet up to one of our offices, but when powered on, we did not get a happy message:

"Invalid PCIe card found in Internal Storage slot. System halted"

After starting to sweat a little thinking about how much time I had spent configuring this machine, I had one of our staff unseat the RAID card and then re-seat it. It booted right up. It must have just come loose during transit. A lesson to me, that even if it is a 70lb server and palletized, UPS/FedEx will still throw it around, so pack well!