Zapier task (GitLab → Quire) works but gives a 404 (but works!)

I have a Zapier task set up (a new issue in GitLab creates a new task in Quire), and it works great. But a lot of times (not always, it seems), I get an e-mail from Zapier saying that there’s a "possible error" they ran into: “Quire: The app returned "404".” And yet, it works perfectly.

I don’t know if they do several tries and like the first gets a 404 for some reason, and the next one succeeds a few seconds later. But still, even if they do that, why would they get a 404 at some point?