as soon as you hear the word "mom" come out of Shigaraki's mouth you freeze for a moment. You are the oldest member of LOV as you are in your late thirties so you somehow "take care" of the younger members like Spinner Toga but especially Shigaraki (who are all in their early twenties). Shigaraki in particular, you immediately noticed how troubled and childish he was and how Kurogiri was keeping an eye on him but after his arrest you started keeping an eye on Tomura and doing things like cooking. It's true that you act almost like the "mom" of the group, but you certainly didn't expect to be called that, anyway from the way Shigaraki immediately fell silent it seems that the word came out involuntarily