In American culture (and, to my knowledge, to a greater extent in Asian cultures) it is polite to refuse offers. Whether it's the last cookie or a ride home, offers are routinely declined with gracious "No thank you"s. Certainly it's fine to accept these things if someone offers it, but it is polite to decline.
Perhaps we are afraid of inconveniencing the giver, perhaps we just don't want the burden of feeling indebted to someone, or perhaps it's just a habitual reaction. Whatever the reason, it seems strange that it is polite to make offers, but impolite to decline them.
My thesis: it is honorable and right to accept the small daily gifts of others. Accepting offers helps cultivate a habit of giving in the one making the offer. The more someone's gifts are joyfully received, the more they will want to give in the future.
If we reject an offer, we are subliminally suggesting that the offer was not welcome, or we are at least slowly training the giver not to give. Just like in training a child, encouragement of a behavior will create that habit, discouragement will create a habit of the opposite behavior.
Just a thought.