[...Well, well. Part of him has been curious about this particular Morgana for quite some time. Judging from her description of Arthur and reference to his father, she's a much younger, presumably less vengeful person than what she'll become.]
[For the present he simply replies to her inquiry, and takes note of her interactions with everyone with intrigue.]
As mentioned by the others, it is indeed magic. Of a mischievous and mysterious nature, even by those who understand it best.