ex messaged me for nye

so i dated someone for nearly 6 months and dumped me last nov before i left for abroad for a long vacation.

he told me he doesnt want to hear from me so i respect his decision and didnt bother reaching out. he removed me from his social medis as well but he ended up viewing my stories so i made my account private.

out of nowhere, he sent me message wishing me well on new years eve and i replied back out of courtesy. what does it mean? why would he reach out if he didnt want anything fron me i find it so odd