He's embarrassed and closes the locket, stuffing it into his hitoe and scowling at nothing in particular.

"We get along fine, her brother did somethin' to this machine and I thought it was gonna attack her. She took the pictures and made this thing. She has one too. She overreacted is all, as usual."

Is that sunburn or is he blushing? It all up to your guess. Despite his insistance that she overreacts, it's completely obvious he's protective and a little possessive of her.