Yes, it might be a dud, it's getting to be that timeframe where you should have seen eggs by now. To be safe, add them a frame with eggs and then check back in a week, and see if they've started queen cells on it. It's getting close to the timing where if they are queenless, they will start laying workers, so the frame of eggs would be a good thing right now. If you do have a queen, then no harm, but if it's queenless, it will give them eggs to keep from turning laying worker and they should start queen cells for you. Good luck!
