I took the "That is so wierd" reaction to mean this is not the first time a girl has said that to Kirk. This pattern likely began not long after wrecking his uncle's convertable and getting arrested-- everyone loves the bad boy. I think his surprised was because she's the first space alien who's ever said that to him. Based on The Original Series, this appears to be the first in a long line of beautiful extraterrestrial women to fall in love with Kirk in after a short period of time. Its a character trait, at this point, like Chekov's "nuclear wessels".