Bjarni was trying to sail from Iceland to Greenland (which he had never been to before) when he was blown off course--he realized the lands he saw were not Greenland and he was in a hurry to get to Greenland which is why he did not stop to explore. His report came as news to the Norse already settled in Greenland so it is highly unlikely that any Norse settlements found in North America predate Leif's voyage.