From Street of No Return, a nice passage:

He was halfway up the steps when the mouse came running down.

Or rather, it came falling down, it must have been blind or sick, or maybe one of them lunatic mice that can't do things in a sensible way. Its tiny furry shape hit him full in the face and instinctively it fought for a hold with its legs. He locked his lips to hold back the startled yell and heard the mouse giving its own outcry of shock. It squeaked as loud as it could, decided this was not the place for it to be, and leaped off.

Whitey shook his head slowly and thought: That almost did it.

He rested there a few moments, trying to forget the feeling of the mouse dancing on his face. He said to himself: Let's disregard these minor issues, you got more stairs to climb, keep climbing.