Washington (CNN) On Tuesday night, Democrats flipped two Republican-held state legislative seats -- one in Oklahoma, one in New Hampshire -- that Donald Trump carried in the 2016 election.

That makes six turnovers from Republican to Democrat in contested state House and Senate races so far in 2017 -- and 26 out of 35 races (at the state legislative and congressional level) in which the Democratic nominee has overperformed Hillary Clinton's showing last November. (Worth noting: Republicans have yet to flip a Democratic-controlled seat so far this year.)

Republicans will, rightly, note that in each of the contested special elections for US Congress, Democrats may have improved on Clinton's performance but they weren't able to actually win. Close doesn't count in politics.

Which is true! As is the fact that Republicans picked up a massive amount of state legislative seats in the Obama era -- well over 900 -- and were bound to give some of them back eventually. And that each race, of course, is unique -- and not necessarily indicative of any broader national trend.

But, we also know from the history of congressional wave elections that there do tend to be canaries in the coal mines -- a race or a set of races that reveal that something is happening out in the country that we need to pay attention to. And the numbers I cited above suggest that something just might be happening.