Stable 1.5.1 updates becoming available on select devices?

I have been messing around with settings on ALL my devices the last 48 hours, and just noticed that some of them have an available stable update to 1.5.1 now.

Oddly enough, I was able to update ONE of my Plug US+ devices, but not all of the Plug US+ devices thus far. Similarly, I updated ONE of my 1 Gen3's to 1.5.1, but some of the other ones I'm checking don't have that update yet.

It looks like the beta 1.5.1 and stable 1.5.1 are the same web ID (seen in the web interface of a device), so maybe that's why some are updating and some aren't?