I'm seeing this https://github.com/drapanjanas/re-natal/issues/99 on 0.5.14, unfortunately.

Doesn't happen on a fresh clone though, so it seems like perhaps a remnant of 0.5.9 or other factor which is bringing it into my app.

Ah, this would explain it: https://github.com/bhauman/lein-figwheel/blob/381ed0ccb3de66c6f4cbf8bb9ccc48c093694baa/support/src/figwheel/client/file_reloading.cljs#L264-L274

Ok, summarized in a ticket.