Feedback is very valuable and is given to you by experts or peers to improve your understanding and knowledge of the tasks you were to complete. Yes you can ask questions about the feedback in order to improve your understanding and plan for improvement. Note there is a difference between asking questions to gain further insight and understanding, and questioning the feedback itself! Your tutors demonstrators and preceptors are there to help you and during your own self-assessment their advice and suggestions should be considered and taken on board. If you do encounter difficulties in relation to assessment or feedback it is good practice to discuss it with your tutor and clarify.