Por que Hermione diz “Esqueça” sobre a mãe de Hagrid quando ela não sabia antes que estava morta?

No Cálice de Fogo, capítulo 23 (Yule Ball) ouvimos Hagrid falando sobre sua família pela primeira vez.

“It was my mother,” said Hagrid quietly. “She was one o’ the las’ ones in Britain. ’Course, I can’ remember her too well . . . she left, see. When I was abou’ three. She wasn’ really the maternal sort. Well . . . it’s not in their natures, is it? Dunno what happened to her . . . might be dead fer all I know. . . .”

E então nós temos mais alguns detalhes de Rita Skeeter no próximo capítulo (Colher de Rita Skeeter)

His mother, we can exclusively reveal, is none other than the giantess Fridwulfa, whose whereabouts are currently unknown. . . . While many of the giants who served He-Who-Must-Not-Be-Named were killed by Aurors working against the Dark Side, Fridwulfa was not among them. It is possible she escaped to one of the giant communities still existing in foreign mountain ranges.

Então sabemos que nem Hagrid nem Harry, Ron ou Hermione sabem o destino da mãe de Hagrid. E então, em Ordem de Fênix, capítulo 20 (Hagrid's Tale) Hermione diz,

“Hagrid?” said Hermione quietly after a while. “Mmm?” “Did you . . . was there any sign of . . . did you hear anything about your . . . your . . . mother while you were there?”

Naturalmente depois de ouvir onde ele tinha ido, ela estava curiosa para saber se ele conseguiu conhecer sua mãe. E logo em seguida ela diz:

Hagrid’s unobscured eye rested upon her, and Hermione looked rather scared. “I’m sorry . . . I . . . forget it —” “Dead,” Hagrid grunted. “Died years ago. They told me.” “Oh . . . I’m . . . I’m really sorry,” said Hermione in a very small voice.

Ela diz "eu esqueci". Mas quando ela aprendeu sobre o destino da mãe de Hagrid quando até o quarto livro eles não tinham certeza se ela estava viva ou morta?