Henderson will miss next week’s Merseyside derby after seeing red this afternoon.
The midfielder was sent off in the second half of the Liverpool win, after he picked up two yellow cards.
Goals from Mohammed Salah, Trent Alexander-Arnold and Roberto Firmino were enough to earn Liverpool the win.
But for Liverpool the win was marred by Henderson’s dismissal, and Klopp has taken some blame.
In his post-match press conference he admitted that he should have seen the signs that the midfielder was getting reckless.
“I think it (the result) tells the story because we stayed stubborn, they defended and counter attacked so we had a few really good moments we didn’t score which is not a big problem if we stay on track,” he said.
“How we closed down the game was just brilliant especially the third goal.
“The first goal was brilliant football and the free kick from Trent (Alexander-Arnold) was a dream.
“It was a good game against a good side.
“We only have difficult places to go to, and Watford is especially difficult.
“The points they have is no coincidence so coming here you are never allowed to take a win for granted.
“Work rate was brilliant, the tactics were good as it is always so difficult to find a solution to the defence.
When discussing Henderson’s dismissal, Klopp refused to be too harsh on the 28-year-old.
“It happens,” he said.
“Jordan Henderson was not happy about his mistake but what a guy he is.
“He has a heart like this so sometimes it leads you on the wrong path.
“We wanted to change him but we were a little bit too late.”