Notification of change requests

[Sylvia21]

A guest notified me that she wanted to change her stay from 5 days to 4 days. Her stay with me is not until next month so she was well within the timeframe for my moderate cancellation policy.  I asked her to send me a change request, indicating that I would be happy to approve the change.  I did not receive any notification from the Airbnb system that a change request was pending and just happened to click on her reseratation today which did bring up the change request.  Why did I not receive notification from the Airbnb system that a change request was pending?