It was probably safer for a ghost not to think too drastically about change. It could untether them completely. The more stable her world is, and the more connections she can make the better of she'll likely be.

Mab considers the question. "Powers are moving in your city, events have begun that cannot be stopped. There is much of interest here. It is important to see the whole picture." It was more than she would tell most people. Perhaps it is the absolute sincerity with which the ghost has refused to gossip about strangers that gave her the freedom to do so. Or perhaps it was a whim. It sounds like a portent but it only observation.