Just found your post, I can't believe no one has at least written to say HELLO..... I call this drooling as I have awaken on several occasions and found I "slept with my mouth open again" pillow soaked in one spot. I do know of several other people who have had this happen. As for if this is a medical condition, I can't help on that. Hope you find an answer!

Did it begin after a visit to a doctor or is it something new?
Usually every individual produces saliva all the time and by reflex will swallon unconsciosly. This is essential to the function of the oral mucous membrane. Your problem might be that u produce too much saliva due to a certain medication. In this case, u should see the doctor who was prescribing u the medication.
Maybe u should consult an ENT specilist to get ur saliva tested.
Try to remember the first time this phenomennon occurred for the first time and whether there are some correlations to visits to a doctor.

Did it begin after a visit to a doctor or is it something new?
Usually every individual produces saliva all the time and by reflex will swallon unconsciosly. This is essential to the function of the oral mucous membrane. Your problem might be that u produce too much saliva due to a certain medication. In this case, u should see the doctor who was prescribing u the medication.
Maybe u should consult an ENT specilist to get ur saliva tested.
Try to remember the first time this phenomennon occurred for the first time and whether there are some correlations to visits to a doctor.

yesss I have heard of that before. What happens is that while sleeping without u noticing u move ur tounge around and since ur sleeping u dun spit out like u would if u were moving ur tounge while awake. I knew some girl that did that. The best thing to do is to sleep w a ���� in ur mouth this way at least someone can benefit from ur drooling problem.