You did not do it for the thanks you might receive, but because it is right.

It is not pessimistic to assert that all through life, we are working on this principle--not that we may receive the credit for what we do, but doing good for the good's sake.

Do not be so rash as to say bitterly--"So much for sacrificing my own comfort!" "Catch me giving a woman my seat again!" and those other foolish, because angry, things which a vexed boy is tempted to say under such circumstances.

Continue in the good way, hoping that "next time" you may have the pleasure of doing a favor to a lady who has the breeding to appreciate and be grateful for an act of courtesy.
Your third question is one difficult to answer.

Are girls as well bred as boys--Yes--and no! Their training lies along different lines.