vagrant box outdated thinks the box is outdated; vagrant box update thinks it isn't

$ vagrant box outdated --global
* 'ubuntu/trusty64' is outdated! Current: 20150422.0.1. Latest: 20150427.0.0

$ vagrant box update --box ubuntu/trusty64
Checking for updates to 'ubuntu/trusty64'
Latest installed version: 20150427.0.0
Version constraints: > 20150427.0.0
Provider: virtualbox
Box 'ubuntu/trusty64' (v20150427.0.0) is running the latest version.

$ vagrant box outdated --global
* 'ubuntu/trusty64' is outdated! Current: 20150422.0.1. Latest: 20150427.0.0

I don't know what to think.

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: vagrant 1.6.5+dfsg1-2
ProcVersionSignature: Ubuntu 3.19.0-15.15-generic 3.19.3
Uname: Linux 3.19.0-15-generic x86_64
ApportVersion: 2.17.2-0ubuntu1
Architecture: amd64
CurrentDesktop: GNOME
Date: Wed May 6 10:10:51 2015
EcryptfsInUse: Yes
InstallationDate: Installed on 2012-07-25 (1014 days ago)
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
PackageArchitecture: all
SourcePackage: vagrant
UpgradeStatus: Upgraded to vivid on 2015-04-23 (12 days ago)