Yeah, whatever button I pushed to upgrade, it did the opposite. It created a new instance of PG and applied the new plan to it. Meanwhile I had to manually copy the data and shut down the old plan/db.

Update: found it while playing with a new project! There's "upgrade instructions" which guide you through the manual process, and there's an option to "upgrade plan" which just reassigns the existing db. Very intuitive!

p.s. Fun fact, if you spin out a new Heroku app (today, Nov 27th), it defaults to free stuff, and makes you upgrade manually, as opposed to just defaulting all the new stuff to cheap paid plans.