The traditional Chinese practice in gift-exchange is quite different from that of Westerners. Chinese are taught as children that in order to show modesty and avoid any suggestion of personal greed, they should decline two or three times when offered a gift. Chinese do not usually accept a gift, invitation or favor when it is first presented. Accepting something in haste makes a person look aggressive and greedy.
Usually when a gift is offered, there is then a seesaw battle in which the gift is offered and refused, offered and refused but finally accepted with appropriate expression of appreciation. The gift is supposed not to be opened on the spot, it is tucked away in a pocked or left on a table until the giver has departed. Only then it would be opened.
One is interpretation of this practice is what the receiver is preserving the face of the giver by avoiding any possibility of evaluating the gift in the presence of the giver and others. Such behavior is simply the Chinese manner.