The exact same thing occurred in 2000 with Cantwell - Gorton. I remember reading an article two or three days before the deadline for the final count saying that both sides believed with the remaining outstanding ballots Gorton had the advantage.
Two days later Cantwell "surprisingly" had taken a two thousand vote lead. Another "surprise".
Republicans, just be glad the Presidential race was not close enough for another late ballot "surprise". Thankfully. Democrats didn't get with in cheating distance.
I'll take the White House over the Washington governor's mansion any day of the week. So would the Dems.
Is there any evidence at all that these ballots are fradulent, or that the ballots in 2000 were fraudulent?
If so, then I would strongly support a challenge to the results. But if they are not, and this is just idle speculation about cheating, then it's no better than those on the left saying the election is rigged.