This is not gaslighting, but it is odd.

What would have happened if you had just said “sorry I’m really busy with work today and won’t be able to meet you at the drop off”?

If this would cause her to act the same way, then there’s something wrong. Maybe she recently did a true crime binge and is feeling insecure about her safety? Or maybe she’s showing signs of mental illness. If you guys are in your early 20s, that’s when schizophrenia typically shows up, and can definitely have some paranoia to it. But, you’d need to get a professional to diagnose something like that.

If it wouldn’t cause her to act like this, then she’s probably just pissed you didn’t do what you said you would do. Maybe you have a track record of this kind of behavior and she’s starting to get tired of it?