I actually did find her reply rather flirty. For me, she was saying something along "try me".

If she'd be in NO intent whatsoever she wouldn't even talk to you and just walk away. Just look at you with a strange face

But alot is about her tone!
Since she gets hit on alot You never know when a girl will counter with sophisticated sentences 99.9% of all approaches fail to bypass


So if it was me, I'd probably have tried (I mean, what do I have to loose with such response?) something like;
If you think THAT was bad, you should have seen/heard *random short story telling*.

Also, you implied you are insecure because you compared yourself to others (where you are the superior one). Never do this, it's a huge risk you are taking.

Saying it the same way, but with an better approach would have been something along those lines;
When I first saw you from behind, I was about to come up to you and be nice. But once you turned around, I reconsidered it a second time