It can happen. The wax capping are very thin and honey is hygroscopic so it will absorb water from the air if its really humid out. I had a similar problem last year, you can put the honey in a room with a dehumidifier and pump air through it for a few days. Commercial producers actually have honey driers for this purpose, but thats because they tend to harvest a lot of nectar with their honey. Are you sure you extracted only capped honey and not some nectar?