I added a 3# package of bees May 14th 2016. They have been building strong, but only recently started building in the second box with a small amount of comb on 1 of the bars in the bottom box. They swarmed last week. When I opened the hive I could see the swarm cells. It looks like they have plenty of room and I know there is probably not an exact answer as to why they would swarm so soon, but any thoughts? What do I do now? Do I need to check for a queen in a few weeks? Thanks for any help.