An "Install RELEASE" icon appears on a newly installed Ubuntu (the flash drive isn't in the usb port)

[Mikhail]

mishka@mishka-B150M-D2V:~$ lsb_release -rd
Description: Ubuntu 16.04.2 LTS
Release: 16.04
mishka@mishka-B150M-D2V:~$ apt-cache policy ubiquity
ubiquity:
  Installed: 2.21.63.3
  Candidate: 2.21.63.3
  Version table:
 *** 2.21.63.3 500
        500 http://ru.archive.ubuntu.com/ubuntu xenial-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     2.21.63 500
        500 http://ru.archive.ubuntu.com/ubuntu xenial/main amd64 Packages

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: ubiquity 2.21.63.3
ProcVersionSignature: Ubuntu 4.8.0-53.56~16.04.1-generic 4.8.17
Uname: Linux 4.8.0-53-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.6
Architecture: amd64
CurrentDesktop: Unity
Date: Thu Jun 1 14:10:45 2017
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz.efi file=/cdrom/preseed/ubuntu.seed boot=casper only-ubiquity quiet splash ---
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)