Eh, it’s fine to cook with. Just don’t let it sit in there and oil your pan when you’re done!
Fun fact: Soap is absolutely the way to clean your cast iron. The old advice of “soap will ruin your seasoning” is based on old soaps which includes lye, a strong base. Modern dish soaps are very gentle and are perfect for cast iron! Note that this doesn’t include dishwasher detergents, those are very aggressive and will ruin your seasoning.