Don Lemon hasn't forgotten about his clash with Nikki Haley earlier this year ... bringing it up as a way to diss her over fumbling a question about the cause of the Civil War.
The former CNN anchor is ripping Nikki for asking for grace for omitting slavery from her answer ... he says she was quick to pounce on him when he called her past "her prime" earlier this year on CNN, and didn't leave him room to ask for grace.
As you know ... Nikki is catching tons of flak for not mentioning slavery as a catalyst for the Civil War in response to a question on the presidential campaign trail.
Nikki's since backtracked, telling CNN she didn't mention slavery because she thought it was so obvious.
Don says he's glad she's clarified her remarks ... adding, "In the spirit of the season, let's see if her actions match her corrected words moving forward."
It's no surprise Don is still sour about his beef with Nikki ... the remark was another strike for him at CNN, and it caused him to back out of an event he was set to moderate.