In Agile methodologies, feedback and adaptation are key principles. If the team members are not confident about the product increment they are building, it's important to address this concern as soon as possible.
Scheduling an additional interim demo with the product owner allows the team to validate their work and receive necessary feedback, which can help them adjust their approach if needed and continue delivering value. This aligns with the Agile principle of early and continuous delivery of valuable software.
References: The information is consistent with Agile best practices, which emphasize the importance of continuous collaboration with stakeholders and adapting to change over following a set plan. This approach is supported by the Scrum Guide, which suggests that it is acceptable for the Product Owner to accept stories during a Sprint, allowing time for any improvements or defect fixing1. Additionally, the discussion on ExamTopics supports this answer, highlighting the importance of early feedback from the Product Owner2.