It's not within the realm of believability. The chance of "human screwed up" astronomically exceeds this being fairly randomly chosen, and the Firefox bug states, (I think this is supposition, not known fact, but IDK)
> The original key generation was flawed - rather than any issue with the produced signatures. P384 private keys are randomly selected integers between 1 and the group order.
> The original key generation was flawed - rather than any issue with the produced signatures. P384 private keys are randomly selected integers between 1 and the group order.
That is within the realm of believability.