I suppose he's afraid you'll catch him.
2 seconds sound clip from Superman (1948) - A Job For Superman (Chapter 5).
You can hear this line at 00:10:51.969 in the Blu-ray version of the episode.
Quote context
[...]
- No, that was really the Spider Lady. I'll never forget that voice.
- But she must be crazy to challenge Superman this way.
- She claims she knows his one weakness. Maybe there is one thing he fears.
- I suppose he's afraid you'll catch him.
- Superman'll be there tonight and so will I. To cover the story.
- Hello, chief. Did you hear the broadcast? You're going to provide protection. Good.
- Why not? They can't trace it. It was sent from our mobile unit.
- Do you think you oughta tip your hand?
[...]