I may have to re-watch the scene but did she give her phone to the kid with some intent of tracking her or having her use the phone in a traceable way?
But yeah even for POI standards there was a lot of double-crossing this week! I suppose it was telegraphed when her and Reece/Riley both background checked each other early on. These two think alike, so maybe we should have seen that both of them had a secret agenda, not just Reece...
Oh, and was this a second week of camera shots from "the Machine'" POV rather than Samaritan? The threat to movement seems to have been well and truly squashed with the new identities and secret phone network. Would Samaritan not realise that there are people talking on phones that it can't listen in on? Or at least it should be able to hear what they're saying via other audio sources nearby?