Normal
This happens a lot with cruise bookings - there must be a lot of TA's who have booked group space on that cruise and the ship only has so many cabins set aside for group bookings........I'm sure a TA could explain this better than I but it is not that unusual of a situation to happen. Your TA should have reserved more cabins than you thought you might need for the group space - any cabins not sold by a certain date are then released back to the cruise line.