Why is Kazu uncomfortable when his wife gives him a watch for his sixtieth birthday in the novel, Tokyo Ueno Station?

The watch Setsuko and Yoko give to Kazu is a symbol of time and Kazu's strict utilitarian lifestyle. Kazu feels uncomfortable when he is given the watch for his 60th birthday because he is "unused to receiving gifts" (151). The family has always been working class, if not poor, so presumably gifts were rare occurrences.