Lost valuable vintage baseball card collection including a Ken Griffey Jr. rookie card in mint condition at Altoona-Johnstown Fairgrounds.

I lost a valuable vintage baseball card collection while attending a sports memorabilia event at the Altoona-Johnstown Fairgrounds last weekend. The collection includes several rare cards, but the one I’m most concerned about is a Ken Griffey Jr. rookie card in mint condition. I must have dropped it while chatting with some fellow collectors. If anyone has seen it, I’d appreciate any help in getting it back!