Cash did not pay any attention to him.

He was busy seeking out a soft, shady spot that was free of rocks, where he might lay Marie down.

He leaned over her and fanned her violently with his hat, his lips and his eyebrows working with the complexity of his emotions.

Then suddenly he turned and ducked into the tunnel, after Bud.
Bud heard him coming and turned from his work.

Cash was not trundling the empty barrow, which in itself was proof enough that something had happened, even if Cash had not been running.