Comment 4 for bug 1533631

After deleting the dhcp6${UUID}-${IF}.lease file and reconnecting the interface the "starts" timestamp is now up to date. Not sure if this is relevant to the internals of dhclient though.

$ cat dhclient6-0775a2a6-a4a1-40bf-bd85-9c3068582dbc-wlp3s0.lease
default-duid "\000\001\000\001\036z\001X\000\037;\275t\205";
lease6 {
  interface "wlp3s0";
  ia-na 3b:bd:74:85 {
    starts 1458668291;
    renew 43200;
    rebind 69120;
    iaaddr 2a02:8011:2007::3 {
      starts 1458668291;
      preferred-life 86400;
      max-life 86400;
    }
  }
  option dhcp6.client-id 0:1:0:1:1e:7a:1:58:0:1f:3b:bd:74:85;
  option dhcp6.server-id 0:3:0:1:ec:43:f6:46:c0:80;
  option dhcp6.name-servers 2a02:8010:1:0:212:23:3:100;
  option dhcp6.unknown-16 0:0:d:e9:0:c:64:73:6c:66:6f:72:75:6d:2e:6f:72:67;
}
$ date +%F-%T --date='@1458668291'
2016-03-22-17:38:11

$ grep 0775a2a6-a4a1-40bf-bd85-9c3068582dbc timestamps
0775a2a6-a4a1-40bf-bd85-9c3068582dbc=1458668288

$ date +%F-%T --date='@1458668288'
2016-03-22-17:38:08