It's unusual behavior, and it's not the only one in that game, including leaving Sweden and the North Sea completely undefended.

You won't be able to get a better feel for if there is anything more than unusual behavior, however, until after the game is over. At that point, you can check the records of the players involved, and see if it is the same accounts playing against each other. I would also recommend checking all the players in the game; the multi-accounters that I have spotted in the past usually don't take a chance and will include several alts in each game in order to ensure that they win.