I dunno, he didnt remember being in the hospital where victoria was treated either until Nami told him. Could be the same "accident" which did lead to Sasha's scar. Or the "carcrash" from his parents, Nika seems to have a somewhat foggy mind if its required by the plot
And apparently "everyone knew Nika form where they grew up" according to Nami. And Nika knows supertopmodel² Elsa deladings without a zane relation (if summer isnt related to the zane's in some way) so who knows. Maybe Nika saved her cat in the past