Does that mean your la nina ended or did it take a vacation for a month?
It means that the La Nina effects aren't completely negating the general warming trend. It was colder during the NH winter than average in many places, probably due to La Nina. March is a transition month, and because warming is causing an earlier spring, this earlier spring translates into a warmer month than average. If La Nina persists, its effect may be more noticeable in suppressing summer temperatures. We'll just have to observe the data.