may be he or her is playing a no vacation tournament
Vacation on Select Games?

No tournament games are indicated.
Perhaps only the games in which it is his current move are shown as on vacation? But that should not be possible according to the Vacation FAQ which says...
"You must have played the moves in all your games before going on vacation (meaning it must be your opponent's move in all of your games to turn vacation on)."
My opponent is marked as on vacation for some games but not others... how is this possible? The only vacation option I am aware of is applied to all of one's current games, not a select few. Anyone understand this?