In the late afternoon we noticed Pot Plant Owl sitting upright and alert. She stared wide-eyed when I said 'hello' to her, instead of doing her usual winking and blinking reply. When the sun set, she didn't leave the nest. Immediately we thought an egg had hatched.
An hour later: Just checked the webcam when Pot Plant Owl flew to the neighbour's roof. There are still 3 eggs. Wonder why the change of behaviour? Perhaps it is any hour now that the eggs will hatch. Maybe something scared or irritated her during the day when we were out - crows, for example.
Will keep monitoring closely.