So, it's like this:
When you play this card after some series of quick cards you will be penalized also. But if you play this card as a first card of your turn, it doesn't penalize you, because you didn't play any quick cards before this card this turn (remember that this is the first card played this turn).
The game has stored information about cards that you played previous turn, but the information which were marked as "newcards" is already lost. Without changing the game engine or implementing the game history module, it cannot be helped.
However the card text may be clarified. "Previous turn" and "Last turn" are two different things. "Last turn" means this turn inluding series of quick and swift cards. "Previous turn" is the one that was played before opponent's last turn (and can also include series of quick and swift cards).
I plan to unify the card terminology and update game manual.