Given the context of a flirty conversation, "haven't" is entirely appropriate and, to some extent, clever since it changes the nuance of her response. I'm not certain what you mean by "taste", since, in that context, the word can be more or less suggestive. But it's also not important.
There are two responses to your innuendo:
You didn't taste me
You haven't tasted me
The first is fairly literal, and actually a bit cold in that it says "that event didn't happen". However the second is the opposite -- it implies that while the event didn't happen, it could still happen -- as in "You haven't tasted me ... yet".
So you can interpret that response as a warm invitation to continue flirting, rather than a less enticing, more straightforward statement of fact. The response is not a direct reply, but rather changes the implication of the sentence by adding additional, unspoken suggestion.