Explain the mood of this excerpt from little brother. provide details from the text to support your answer.
she gave me a long hug, and i noticed how thin her arms had gotten, how saggy the skin on her neck was. i always thought of my mother as young, pale, rosy-cheeked and cheerful, peering shrewdly through her metal-rim glasses. now she looked a little like an old woman. i had done that to her. the terrorists had done that to her. the department of homeland security had done that to her. in a weird way, we were all on the same side, and mom and dad and all those people we'd spoofed were on the other side.