Hi Mary,
As the rest have said, what your husband is experiencing is totally normal. My husband had and still does have fluid build up under his chin. Especially in the morning when he wakes up. We took him to my facialist and she gave him a lymphatic drainage massage and it really helped. Now every morning he massages his throat and it helps the fluid that has built up to "disburse" so to speak throughout his body. Give it a try, I bet it will help.
Good Luck,
Shelley