The short answer: Check back in a month.
The shift hasn’t lasted long enough to merit a reassessment of the national political environment. But there are reasons to think it could.
It can be hard to remember, but we’re still nine months from the election. In a presidential election year, the New Hampshire primary might be coming up next Tuesday. So it is quite early to care about every little bump on the congressional generic ballot trend line.
And, to some extent, the Republican gains look like another little bump. After last month’s Democratic surge, it was reasonable to expect the polls would revert toward the longer-term mean, which had been something closer to an eight- or nine-point Democratic edge.