User blog comment:Knightofthecart/Morgana in Arthur's chambers/@comment-4623180-20120317154229/@comment-4650675-20120317201005

He must mean what Gwen said on 1x01, that "some people are made to be queen" when Morgana appeared and was seen talking to Arthur, to which Merlin replied "yeah!". It was not directly mentioned but it does make an indirect reference to Arthur marrying Morgana.