Could be because BWI's Dispatch Center is collocated in the same room and they have bother fire and police on their consoles and they may have accidentally selected that Talkgroup on their console, it could be that there was only one dispatcher on at that time and they had the Tac 2 selected as they were trying to monitor two talkgroups. It could have been a number of things, maybe it was a one time thing. things do happen, I dont see it as a big deal!!!