I def would've taken it as her trying to flirt. Not sure if ur response was ideal - maybe should've ran with it a bit instead of backing off and feigning innocence. But at least u got a chuckle from her out of it.

Id maybe try being less vague and evasive going forward. I think she wants to sext, but ur still saying stuff like "u will have to find out on our date". Not all girls are coy, u can be direct with some of them.