Apple → [Watch] How did my Watch get updates when I was disconnected?

I left my iPhone at my desk (there's no WiFi at my office). I was in another building approximately 1/4 mile away (the building has WiFi).
My Watch showed the Disconnect icon, yet I was able to get a few app updates. The updates were current, that is, the event had just occurred, they weren't old updates from last night that showed just showed.
How did Watch get updates?
Thanks!

Have you used the WiFi on your phone in that building previously?

The watch will connect to known WiFi networks to get updates for apps that run directly on the watch.

Yes, it's a fitness center I visit every morning.
Thanks!

(you're very smart!)