I got that error message again at 5:50pm today, but that's the first time it's happened since your post and I have been on MW a lot in that time.
I also got it only once in that time. The upgrade does seem to have helped.
Anyway, when I got the error I went back to Cloudflare and they were able to provide some logs which show an issue with how Railgun is setup with the host. So I'm now waiting for the host to investigate further based on that evidence.
Ultimately, if we end up with no solution I'll just disable Railgun.