Shy and friendly girl turned rude and avoidant?

There's this shy girl I know and kinda like. She is very friendly and polite with all people, to the point where she almost seems afraid to come off as rude. We sometimes texted, it was basically always me who initiated but I could tell that she liked me a bit. Didn't see her much in person, but when we I did there were also subtle but definitve signs of her liking me in some way. Things were going reasonably well, but I didn't ask her out until recently to which she replied that she was busy. She didn't propose an alternative, didn't tell me what she is busy with until I asked and I know for a fact that she isn't all that busy. Now, I take that as a rejection for now, but I've been wondering at her change of behavior. The change came right around v day which I think is the point of time when she expected me to ask her out and which I should have done. She used to be more engaging in texting, replied quicker, now she seems to be deliberately ignoring me. She is taking like 12 hours to reply, avoids me at occasions where we might run into each other, that kind of stuff. Another thing which is actually a silly detail is that she is waiting until the last possible moment to view my Snapchat story whereas she used to do that within a few hours. Now, normally I would just move on and accept the fact that I waited too long but in this case I feel like her ingnoring me is very untypical for someone like her who acts friendly to anyone willing to give her a bit of attention and also very deliberate as if her behavior has a clear purpose or goal. What should I do? I don't feel asking her out because it feels like there's a conflict between us, so should I ask her why she is mad or acting like that? If I had to guess I'd say she is mad or frustrated but intent on clearing things up...
Shy and friendly girl turned rude and avoidant?
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