Mandarin Magic

I was on the phone to Mater when I silently and deftly peeled two small mandarin oranges and subtly slid a juicy segment into my mouth.
Not, apparently, quite as clever and underhand as I'd imagined.
"Are you eating fruit?" Mater wanted to confirm. "It's good that you're eating fruit."
In return I begged to learn how she knew.
Oh, she just did, that's all.
That's all. As if it were an ordinary, everyday deduction with nothing creepy or invasive about it whatsoever.
"Oranges are best for you. Good eating."
"Ah come on," was my retort, my alarm increasing, "how on earth are you doing this?"
"Mandarin, is it?"
I can't express too much about what happened to the finer hairs on the nape of my neck. The word 'prickle' doesn't quite cover the matter in the chilly, off-kilter way I would hope for.
At least- I clung feebly to this- she was wrong about the count: I was eating two of them.
"And I'd go so far as to say you're after peeling not one but two mandarins."
The funny thing is, we don't even keep oranges in the house, as a rule; we're more likely to have apples and bananas than oranges, so it's not like I make a habit of eating the things.
Mater refuses to divulge her strange, unearthly secret, at least for the time being, so I'll just have to go on wondering, and asking at intervals.
"Magic," she sometimes replies when I ask and she's feeling inclined to expand a bit on the nature of her talents. "A spot of mother magic."