Grapefruit Reference

Was this supposed to be an "inside" joke:
James Cagney and Mae Clarke are at the train depot, looking at travel folders to decide where to go.
When James is looking at the one for California, he says something like, "See where fruit is grown: avacados, oranges, lemons, grapefruits..." at which Mae gives him a quizzical look and grabs the folder from his hand.
Of course in 1931, they did the famous scene together where he shoved a grapefruit in her face!
A coincidence?