When Petunia saw that Todd had her hairpin, she was just overcome with shock because she had completely forgotten about it. It takes her a while to process everything and then she feels intensely embarrassed about her actions (in chapter 1). (Also, she realises that Todd has probably figured out what she was doing at his window that night and is just freaking out about his opinion of her.)

Todd smirks because he knows something Hana doesn’t know (aka what happened that night when Petunia was at the window to retrieve the hairpin etc etc) and just wants to rub it in her face.  

uhm, I wonder if I answered your question? SOB not sure if I understood the question completely HDSIUHDAUDA *lies down and rolls over* PLEASE… TELL ME IF I DIDN’T ANSWER IT OR NOT AND I’LL TRY AGAIN…