I had cockatiels and came home to an egg, I ran out and bought a nest box and my cockatiels raised quite a few babies together. It was pretty funny the mom would not always be good and sit on the egg so the dad would chase her around pecking at her, then give up and go do it himself

It is strange that it has taken this long, I don't know if tiels have eggs unless they have been fertilized, have you seen any ummm romance???