It's neither, actually - Susan is wondering whether the people she's left behind are worried about her. It's not a concern she had in Narnia, not even once. And isn't that queer! Her siblings were with her, yes, but their parents and the old professor were all left behind, and it was as if they just... forgot.

Perhaps Susan's natural tendency is to forget, then. Forgetting to worry about her family when she was in Narnia; forgetting Narnia when she was in England. She'd forgotten to worry about Ingrid and Miriam, too, for months and months. Perhaps it's that she remembered at all that's queer, now. Except now she's had experience being the one left behind, hasn't she?

It won't do to ruminate on this now, though. She's got better things to do with her time. "It's no matter," she says, and shrugs it off briskly.