Husband's grandma gave Four Month old ice cream! So mad! What can happen to baby?

She works at a store and we took baby to see her. I walked to the bathroom and came back and saw baby pushing a spoon away that the grandma was holding then she put the spoon in baby's mouth anyway. Well come to find out it was ice cream. My husband said she wanted to give baby some he said it would probably help since baby is teething. I'm so mad. Now my husband googles and says babies shouldn't have dairy till a year old. Baby spit it out some but I'm still so mad. Will my baby be okay? I'm so worried! What is the worst that can happen? 😭😭😭