Ex GF messaged me 3 days after break-up. Advice please

My ex girlfriend i really loved dumped me on Monday for being really clingy and needy. She acted really cold and didn't want to talk to me that day. She basically said: "forget it, it's over". I was really shocked, tried calling her but she hang up so i just texted her: "Thank you for everything, if you end up changing your mind - you can call me since i'm leaving the door open. Love you". However, 3 days after the break-up she messaged me midnight Wednesday on messenger with a random joke and we had a short fun conversation for like 20 minutes before she responded with: "your given minutes for today ran out, good night". What is this supposed to mean lol? Is she just playing with me, trying to get her ego fed or do you think she actually still cares and started regretting her decision after dumping me 3 days ago?

I'm not sure if i did the right thing responding and chatting with her. Maybe i should of done the no contact thing and ignored her. She didn't mention or talk about the relationship during that chat though.

We been together for 6 months and it was a "long distance" relationship. We used to meet up twice a week.

Thoughts?