Ex boyfriend still communicates with my mom??!!

Yeah, so, I somewhat recently broke up with my boyfriend. Soon after, he blocked me on social media and my number for what I’m assuming is because of hurt feelings. That’s fine, but the weird part is, he continuously messages my mother about random things, likes her pictures messages her about every couple of weeks or so. My mother mentioned this to me and we both agree it’s pretty weird and maybe he just wants to get under my skin. If she doesn’t respond, he’ll message again and he never did this while we were together. How should I or should I, approach the situation?