What effect does Leper's appearance at Devon have on Finny?

Leper's appearance only serves to cement Gene's description...... that Leper was crazy.

I turned incredulously. “You saw Leper?”
“I saw him here this morning, after chapel. He was—well, there’s nothing inflamed about my imagination and I saw Leper hiding in the shrubbery next to the chapel. I slipped out the side door the way I always do—to miss the rush—and I saw Leper and he must have seen me. He didn’t say a damn word. He looked at me like I was a gorilla or something and then he ducked into Mr. Carhart’s office.”
“He must be crazy,” I said automatically, and then my eyes involuntarily met Finny’s. We both broke into sudden laughter.