Car Seat Scare

So background info we have a Graco click and connect car seat that came with a stroller travel system. And we always check that the base is tight when we connect the car seat to the base. But we just got home from shopping and I had checked the seat before we left Walmart. I pushed the button to release the seat and pulled the seat out and the entire base unhooked. We had the base checked by an inspector and he showed us how to properly install it. Has anyone else had this happen?!?