A recently conducted docker push to Quay shows the wrong timestamp for one or more images.
The timestamp we show for the Changed field is generated by the Docker client when the image is created. If the time on the machine on which the image was built is out of sync, the timestamp shown will be different on Quay as well. Usually this means a machine needs to be synced with NTP.
Docker for Mac users are likely to have their clocks get desynchronized when their computer is put into sleep mode or hibernation (ref).
The following is command will force the Docker virtual machine to synchronze its clock:
$ docker ssh -C 'sudo ntpclient -s -h pool.ntp.org'