Two possibilities:
1) The descale function was started, either by you or the ghost in the machine
2) A clamp that holds a water tube connection tight is loose inside the oven. I've seen a couple of reports of this. If you unscrew the rear of the oven of the oven, you can see the connection and can tighten it. Of course, that may not be something you want to do. You can see what it looks like here:
Anova's customer service is variable, so you'll just have to wait for a reply.