Car seat question?

I have a infant car seat that clips into the base. I have not installed it in my car yet but I have noticed that the back of the car seat- the end where the baby's head would be- lifts out of the bases maybe an inch or two. The other end is clicked in tight and doesn't move. The car seat does not come out of the base unless I unhook it. My question is- is it normal/safe for the car seat to come out of the base like that?