This is what happens when I am using dual extruders. What is really strange is it only happens on a certain layer (not sure which layer it is) and happens in the same spot every time. Different models get different spots. It happens with all my multi-color prints.
It only does it for the color that it just finished, not the one it's about to start. It's like it should be retracting at that point, but it's actually extruding. It's not like a little oozing, this is a significant amount.