Hmmm I hadn’t considered the fact that we’re supposed to be suspicious of her. I just assumed that Poe would be mad at her, trying to convince her that they have this brand new hyperspace tracking technology, and then Holdo is all like, “Oh really? You mean technology that is theoretically impossible?” So Poe sends Finn and Rose on their secret mission because it seems like Holdo doesn’t believe him, but in reality she was just being prepared for every possibility like a good leader should be, and she wasn’t sharing her plan with any underlings until she was positive the spy theory was wrong.

And yeah, I figured the fact that the FO mysteriously discovered their base’s location would lend credence to the spy theory.