Broke no contact after 3 years

So I (23M) broke no contact with my ex (24F) after she unblocked me on facebook last month. Her sister posted on ig that my ex finally graduated from college. The thing is that I saw that and for some dumb reason decided to congratulate her on whatsapp (I tought I was still blocked but kinda decided to get my feelings out of my chest) so I wrote a text, send it and deleted it right after aswel as the conversation. A couple minutes go by and she texts me: "Hey! Its okay, you didn't have to delete it. I just got to read the first two words. It said congrats so thank you". Then I said that I was just happy for her and wanted to congrat her to which she responds with "its okay and thanks again".

I know that this is dumb, that it was a simple convo but it leaves me wondering why she wouldnt reach out first. Why I as the dumpee feel the need to seek her from time to time. Especially now that I have made progress healing.