underdone

I have been using a recipe for french bread that normally works very well for me. However, once in a while I will get loaf that looks done, temperature about 205 degrees, but still had some moisture close to the crust. I use a Kitchenaid to mix and knead and using the same ingredients and amounts my dough does feel more staturated from time to time at the end of the kneading time. I think I should add more flour to correct but am not sure what the effect of over kneading would be. I am using good ingredients, King Authur flour, filtered wated, etc.. Comments appreciated.