My Husband Had A Graft Made From His Palate Attached

My husband had a graft made from his palate attached to cover the root area of a tooth. The procedure was finished by 1;30 pm today, about 4 hours ago. He is still getting very red blood on the cloth he is holding against the palate guard. He has tried holding cold water in his mouth, till it warms, and is now trying the tea bag. How long can we wait before getting worried?
Thank you, Pam Stewart