This should have been in the pedants thread...zheesh.
OP describes him as a CHAP, but she's offended at being greeted as a girl? Maybe he was influenced by the Boots beauty advert which used the music for Here Come The Girls, for women of all ages.
He certainly did not mean to be disrespectful and if he registered her reaction, likely will not greet her again at all for fear to offend.
Lighten up... OP and be glad you can get out, socialise, and have a church and a congregation to interact with. Some people are shut-ins and see no one day in and day out. They'd be happy to trade places with you just to hear a sincere cheerful greeting full-stop.
Namaste, as my neighbour greets me. 