I was hoping someone could help me get perspective on a situation.

I went out with a girl who acted very interested on our first date. Saturday, day date, walking around the city, no alcohol. She was always the first to touch me to grab my arm, or cuddle up. We ended at my place and made out/heavy petting for about an hour. She asked me multiple times to goto a BBQ with her, and I declined since I thought we had spent enough time together for a first date. She was trying to make plans to see me again on her way out the door, and I said we would figure something out.

I texted her the next day, which was probably a mistake, but just said "Good-morning ". No response.

3 days later there was still no response so I tried her again by texting her something related to a joke we shared. It took her 4 days to respond, and it wasn't much of a response.

What's going on here? Has anyone experienced this who could provide some insight? Maybe she's a flake, busy, or seeing someone else. It might not be worth trying to dissect, but I feel like there is something to be learned from this to help avoid it in the future. Any help would be appreciated.