I think you mean to say bottom driver and not port.

It sounds like Axiom was pretty quick with the troubleshooting so I suspect they knew the driver had a latent defect.

If you have another speaker kicking around somewhere, you could try that to allay your fears about any electrical shenanigans. My bet however is that Axiom knows what they're talking about.

House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated