Given your boss's relaxed response (scheduling the meeting, a joke) - I think it's best to let go. Instead, focus your energy on Friday. This meeting is a good opportunity to have a constructive discussion. 

1. Come prepared with specific examples of areas where you'd like to grow
2. Discuss concrete ways you can take on more leadership responsibilities
3. Work together to create a clear development plan with measurable milestones

Your frustration is understandable - you're invested in your work and seeking growth. The message to your manager, while charged, opened an important dialogue about your career development. Focus on turning this into a productive dialogue about your future at the company.