Moving out notice and NHI

Hello,
I was exchange student in fukuoka from september 2017 to march 2018, my visa was for 6 months. when i arrived i suscribe to nhi, but when i was about to leave japan and return home in march 2018 for personal reasons i didnft had time to tell the municipality that i move out and also i didnft return my nhi card but i payed all my premiums which was ajusted to the visa time i think (from september to march), next time i go to japan will i have some problems with the municipality ? Because my card was about to expire in march when i left japan so maybe it wasnft necessary to withdraw.. but i want to know if it was a bad thing that i didnft sent the move out notice and now there is an another exchange student who live at the dormitory room where i was in fukuoka.
Thanks for your reply and sorry for my bad english !

if you "open", you should "close" by yourself.
you must follow the universal rule if you are an adult.