Is the unopened half gallon of lactose free milk bad?

i left an UNOPENED half gallon of lactaid lactose free milk on my kitchen counter for 20 hours. the room is about 60 degrees due to it being an old house and so cold out. the counter tops are granite and hold cold pretty well. i havent opened the container due to still having milk left, but im curious if i should go get another or not. i guess as long as it smells and a small taste is good i should be fine. right?