Good question. On short time scales like days or even weeks there can be variability in the anomalies across the tropical Pacific including the ENSO regions. To see if this sort of development is more than a blip, we'll have to wait for it to show up in the monthly records.

Looking at the subsurface, it does appear that there is a dwindling amount of cooler than average water which would suggest that La Nina is eventually going to end. But there can always be periods before then where immediate conditions can lead to a momentary increase in cold anomalies at the surface.