Elon Musk at SpaceX in Brownsville, Texas, May 27, 2025. Marvin Joseph | The Washington Post | Getty Images SpaceX filed for an initial public offering a week ago, and Elon Musk is already creating confusion. Days before the reusable rocket maker is scheduled to start pitching its story to investors, Musk took to social network X, which is owned by SpaceX, late Wednesday to explain details of the company's recent partnership with competing AI startup Anthropic . His comment included a potentially material aspect about their deal that wasn't included in SpaceX's 300-plus page IPO filing . Earlier this month, SpaceX said it was leasing unused compute capacity at its Colossus 1 data center in Memphis, Tennessee, to Anthropic.…