it's not uncommon for swarms to have virgin queens. don't know if you have drones still, but you'll need to keep an eye on them or ID a mated queen when you get in there. also, i have gone after "swarms" and found that the main swarm has gone, but there's a small ball of bees that were left behind. in that case, there is no queen.
just watch and see and be ready to make a decision if it's needed.