Originally posted by AngelZoo

I can't think of anything which has changed in the past 1 1/2 - 2 weeks however. Perhaps they will benifit from more wet food in their diet right now then dry, to make up for the lost moister.
Did you open a new bag of food in the last while? Maybe the formulation of the food is slightly different? I would try adding more wet food and if it still continues maybe a vet visit is in order.