Why does ghost look at Jon as a stranger in Jon VI?

[Aemon XVII]

She gazed at Ghost. “May I touch your … wolf?”
The thought made Jon uneasy. “Best not.”
“He will not harm me. You call him Ghost, yes?”
“Yes, but …”
“Ghost.” Melisandre made the word a song.
The direwolf padded toward her. Wary, he stalked about her in a circle, sniffing. When she held
out her hand he smelled that too, then shoved his nose against her fingers.
Jon let out a white breath. “He is not always so …”
“… warm? Warmth calls to warmth, Jon Snow.” Her eyes were two red stars, shining in the dark.
At her throat, her ruby gleamed, a third eye glowing brighter than the others. Jon had seen Ghost’s eyes
blazing red the same way, when they caught the light just right. “Ghost,” he called. “To me.”
The direwolf looked at him as if he were a stranger.
Jon frowned in disbelief. “That’s … queer.”