Answer:

Japanese etiquette requires a “return gift” for almost every gift received, but this is not the case in America. There will always be occasions to invite the person to lunch, send a birthday present, or pass on an extra theater ticket, so wait until that time to “return” your appreciation. Running out to buy a present to “give back”, on the contrary, diminishes the meaning of the original gift. It will not make the other person especially happy.