It followed him to his old stomping grounds, the Metrodome, on Monday afternoon as the Twins beat the Sox, 10-4.
With one out in the sixth inning, Pierzynski grounded into a routine double play to end the inning. But replays showed Pierzynski stepping on the inside edge of first base, possibly nipping Twins first baseman Justin Morneau with his spikes.
Manager Ron Gardenhire bounded out of the dugout and became irate, arguing with first-base umpire Greg Gibson. Third-base umpire Charlie Reliford came over to try to calm Gardenhire down, but the spectacle went on while Twins fans stood and cheered.
Gardenhire explained after the game that he was "fired up," because Gibson had come over to his dugout and made a slashing motion across his throat to signal that he wanted the Twins players, who were upset about Pierzynski's baserunning, to quiet down.
"I was just reacting to an umpire pointing to our dugout telling us to be quiet," Gardenhire said. "That really irritated me by doing that. I didn't appreciate him doing that. Greg is a great guy over there. He was trying to calm our dugout down, and I just didn't like that thing that goes across the neck. That really irritated me."
Pierzynski said he was unaware that he hit Morneau, and did not do it intentionally. He said he tried to apologize to Morneau during his next at-bat, but that he will do it again if he has to. The questionable play in the already intense division rivalry elicited more boos from the fans than Pierzynski usually gets and skepticism from some players.
"Hopefully it's behind us," Twins third baseman Nick Punto said. "I don't really want to make any comments on that, but you don't want to get anybody hurt in this game for no reason. It's behind us and we'll move forward."
Pierzynski did his best to put the incident behind him. Immediately after the game, he met with Gardenhire and explained his side of the situation and offered an apology.
"I didn't feel anything. I guess he thought there was. If there was, I'm sorry. I didn't mean to do anything. I didn't feel anything," Pierzynski said. "I have nothing but respect for him and Gardy."
Morneau did not have much to say about the incident, and seemed to want to put the play behind him.
"He clipped my foot a little bit but whatever," Morneau said. "It's done."
There had been concerns the drama would linger after Pierzynski tried to talk to Morneau during the first baseman's next at-bat but was ignored. Morneau said he was just trying to get ready to hit and that he isn't trying to let this carry on much further.
"It's one of those things that happens sometimes with your foot hanging out and sometimes it gets hit," Morneau said. "It's happened [to me] a couple of times earlier this year."
Twins center fielder Torii Hunter, Pierzynski's former teammate, explained that Pierzynski's persona off the field is much different than his on-field bad guy persona.
"A.J. is a nice guy off the field, but on the field, I just think he tries to get in your head a bit," Hunter said. "I don't think he meant anything by it."
But winning pitcher Johan Santana had another view on the subject.
"In this game you have to earn respect and not ask for respect. I respect everybody so I'm not asking everybody for respect. I think you have to earn it," Santana said. "If you keep doing stuff like that and keep playing like that, I don't think you are going to earn it."
Leslie Parker is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.