What's wrong with my Firefox?

Nothing wrong. Nightly has usually two releases a day. Sometimes, for testing important features, even more Nightly builds are made on a day, but this is not the case. If you check the time stamps, they come from three days, with two builds a day tops: 05/05, 05/05, 05/06, 05/06, 05/07 — so that all checks out. Why it took you through all the hoops and updated individually, instead of just the latest build right away? That's a good point, and normally should only update you to the latest version, unless the updater wasn't aware there's something new until restarted — that's a good thing to watch for over time, if it still exhibits after a few updates.

If several builds a day sounds inconvenient and you don't really need all the bleeding edge changes and experimental prefs, you can move to the Beta/Dev channel that's one cycle behind Nightly, which only gets about 2–3 updates a week normally.