I finally conducted a full inspection of one of my hives. Previously I had only verified that they had brood, stores, etc. When I pulled frames from the bottom box I saw a handfull of chalkbrood mummies on the bottom board. The hive is building nicely and doesn't appear to have any problems right now. I suspect the chalkbrood was from late winter / early spring.
I had planned to requeen the hive this fall anyway. Should I requeen sooner? Or just stick with the original plan? This is my first experience with chalkbrood.