So in the original specification, if B failed the non-square test, it would start over with the next seed and regenerate both A and B. In the RFC version, it w

So in the original specification, if B failed the non-square test, it would start over with the next seed and regenerate both A and B. In the RFC version, it will regenerate B until it is square, then do the other security checks. That's unfortunate, but the generated curve should still satisfy all the requirements. There is little room for this to have an actual security impact. You would need an unknown attack that the original specification did not guard against, but randomly happened to avoid by its choice of seeding for the RFC method to be worse.