easily offended

i am the easily offended 'touchy' type, i soon get offended and annoyed with people....like earlier at the supermarket, at the checkout, when i finished paying for my transaction the girl said '' see you again''.....and i got offended at the use of the word 'again'...i didn't like that at all...i don't like that word as i think it does not apply to me...i handled it by remaining civil, saying ' goodbye' and exited the store....but i still felt offended by her using that word.

any opinions or advice on this valued.