Depends on how you define things. The fact that a gas car will have issues with very cold fuel or fuel outside an octane rating range is not a design flaw. But

Depends on how you define things. The fact that a gas car will have issues with very cold fuel or fuel outside an octane rating range is not a design flaw. But it is a thing you need to know. You could say they learned something new about the rocket's exact "needs" and performance envelope, but you could also say that this sensitivity is something that should call for a design rev. Answer is likely yes and yes.