Grown up kids

I don't know if this is an affliction that only we are suffering from, so would like to hear from other members.

My wife and I have children from previous marriages. The eldest of them are now approaching forty. It now seems as if they have become confused about who are the parents and who are the children. My eldest son and OH's eldest daughter, who are not in contact with each other, are both speaking to us as if we are either inexperienced children or old people gone gaga.

We are both getting pretty fed up with this to the point of my not knowing whether it is my wife or I who will lose our cool first and tell one or other of the cheeky sods which way is up.

Is this unusual?