I have received great information from this forum so hopefully this is the best place for this question:

My mother is moving into a brand new home down the road from us and we got to talking about installing new locks around her house as I have always heard (and followed practice) that when you move into a new home, always rekey the locks. Apparently the builder has told her to go around to all the locks once she moves into the new home and by using her new key the locks will reset themselves to fit that key. Apparently it is a new home thing. Has anyone heard of this before and how likely is it? Apparently there is one key that the builders/etc. can use and once this "magic key" is inserted into the lock, the pins reset and the old key the builder has no longer works, therefore preventing one from having to change locks once they move in.