Ladies and Gentlemen,
The little criss-cross of thread that holds the vent closed on the back of your new coat is meant to removed before the garment is worn. It is only there to keep the vent flat in shipping.
Cousin of same advice: the label on the outside wrist of your new sportscoat is meant to be removed.
The vent tacking isn't quite prêt-à-porter - you have to do the finishing.