Closing a migrated question appends the close time to the "migrated from" message. Either the migrated time should be present all the time (it's currently not there normally) or closing shouldn't mess with the "migrated from" message.
http://img253.imageshack.us/img253/9128/lieso.png
http://img547.imageshack.us/img547/8282/liemso.png
So, when was this migrated?
Of course, it was migrated 10 hours ago, but it was closed 1 hours ago, and SO smashes the migration time with the close time.
So much for a bounty on this - isn't anyone going to look at this bug?
ClosedTime
(since it's a close reason on the original site), and closing it on the new site overwrites that field