From what I've heard it is extremely common for BD's to have the parasite coccidia. Most BD's have this at low levels in their system and provided their immune system is all working well this is fine and they just live with it. It is only when their immune system is weakened, parasite levels increase and they will then require treatment.
From what you've said your dragons are eating and poo-ing regularly so the chances are they are fine, with no or low parasite levels. But I really don't think you need to worry, even if they do have raised levels, it can be easily treated. However it is important that you catch it early on
