When the glands make too much saliva, you may experience drooling. Drooling is normal in the first two years of life. Infants don’t often develop full control of swallowing and the muscles of the mouth until they are between 18 and 24 months old. Babies might also drool when they’re teething.
Sometimes drool can lead to a rash around the mouth, owing to irritation that arises from excess moisture. To keep drool from getting in contact with baby’s skin, do wipe the drool off often with a soft, gently cloth. It’s important to wipe it down. Teething can cause an excessive amount of drool to drip down the back of your baby’s throat. This can sometimes cause your baby to cough.

My guess is that it probably has a lot to do with teething.