This is either a very big deal or not at all a big deal, depending entirely on one's disposition.Count me in the "not at all" camp. Look: whenever a candidate wraps up a nomination he gets a bounce in the polls because there's now a concrete person for people to rally around. The Democratic nominee will get one too eventually. (Though I'll concede some worry about just when "eventually" is going to be for the Democrats.) Then the conventions will roll around, and both candidates will get bounces from that. And then the campaigns will begin in earnest.
It's always better to be ahead than behind. But March matchup polls aren't even like comparing baseball scores after the first inning. They're more like squinting from the bleachers to see how good everyone looks during batting practice. Though that might be unfair to batting practice. And bleachers.
Bottom line: you'll actually be better informed by not looking at polls like this than you will be by looking at them and then trying to ignore them. They're worse than useless at this point.