Wasn't that why he called? To ask you not to mention it?
5 seconds sound clip from the Back for Christmas (Suspense) classic radio play.
You can hear this line at 00:17:15 in the radio play.
Quote context
[...]
- He's going to put some unclassified... wild orchids down there. A Devil's Garden if you please.
- That's Herbert, though. It's really quite simple however, once you find out what he's up to.
- Now take that telephone call he put through to you a few minutes before you arrived, Freddy...
- To me?
- Hubert wanted to surprise me about your plan to meet us in New York next month.
- Wasn't that why he called? To ask you not to mention it?
- And as for my going to America...
- Now, come, come, Freddy, you may as well confess. Hermione has just found me out again.
- But, Hubert, old chap, I really don't...
[...]