Valentine held Youkilis responsible for the rift between the two.
"I got nothing about any of that stuff," Youkilis said before a game against the Kansas City Royals. "I'm over all the Boston thing of this year. There is a lot of great past history, but the focus is on the White Sox."
The Red Sox traded Youkilis on June 24 to the White Sox, where he entered Sunday hitting .316 with 15 RBIs in 15 games. The White Sox open a three-game series Monday at Boston.
On April 15, Valentine said: "I don't think he's as physically or emotionally into the game as he has been in the past for some reason."
"I think the comment I made early, he made a big issue out of, and I don't think he ever wanted to get over it," Valentine said earlier Sunday.
Entering Sunday's game, Will Middlebrooks, Youkilis' replacement, was hitting .125 with a home run and two RBIs since coming off the disabled list on Friday.