And, it's another indication that, whatever's going on with surface temperatures, the big massive ocean is warming and, hence, expanding upward. (Roger Pielke Sr, among many others, emphasized this: "...the importance of monitoring the variability and trends of ocean heat content as the most appropriate and accurate way to assess global warming and cooling (i.e., the radiative imbalance of the global climate system)."
Back during the 2011 sea level dip, scientists were saying that the El Nino-to-La Nina had put a lot of water (via rainfall) onto land, and it would drain off in a year or so and sea level rise would be back on track. Some tried to pretend otherwise. Guess who was right.
Here's NASA's Josh Willis talking about the dip in sea level just over a year ago, and saying it was unlikely to continue:
As he says at the end, "the long-term outlook is definitely one of rising sea level and global warming." Don't bet against it.