DHCP Leases - Last-seen property display inconsistency

ROS 6.17, MIPSBE devices.
I have found an inconsistency between last-seen property display in CLI and Winbox.

CLI displays in weeks and days and time, but Winbox displays value like “49638d 09:30:37”.

I checked the documentation, but this poperty is not documented!
(http://wiki.mikrotik.com/wiki/Manual:IP/DHCP_Server#Properties)

Sent e-mail to Support, [Ticket#2014072866000198].