No, you havent. Not this build. Its a security update. (Build 15E302) It was only released Tuesday. Check your updates under Settings/General/Software Updates
YES I HAVE!
When I go to Settings, General, Software Update and it says:
IOS 11.3.1
Your software is up to date.
It’s been like that for a week.
Hence, my comment ‘I’m not a developer, etc.’ I’m very knowledgable.
Please don’t give me any pushback on this.