There isn't anything new about this. Older versions of macOS allowed for setting "Allow all" for opening apps from "unidentified developers" and it may be that you have this enabled. Also, opening an unsigned or ad-hoc app on the machine it was compiled on does not trigger quarantine. If the build comes from the CI build system set up by IOhannes, I believe it automatically signed using the IEM account and so is "verified" hence no warning.
Just in case this isn't done yet, would it make sense to offer the CI build system binaries on Miller's webpage as well so downloads of the same version show identical behavior on OS X?
(2 cents) Peter