Wasn’t it natural that Paul should consult with those who were leaders in the church, who had known the Lord during his earthly ministry? Yes, it would have been natural, and if this had been any other calling to service in the church he might have done so, but the call to be an apostle was unique. To share or confer with the other apostles would have risked compromising his apostolic authority by opening up the possibility that he did not speak independently.