Rookie third baseman Matt Chapman was ejected from Wednesday’s game in the fourth inning after a testy exchange with Angels catcher Juan Graterol that A’s outfielder Khris Davis said exemplified what a team leader Chapman is becoming.

Chapman said he was trying to stick up for teammates Graterol had accused of stealing signs. “I think this stemmed back to a couple of days ago. They thought we were relaying signs from second base and they also thought a couple of hitters were peeking at catchers’ signs,” Chapman said.

“When we were digging into the box today, the catcher kept staring at the hitters as they were digging into the box. That’s not a very comfortable feeling having the catcher staring at you. It’s a little disrespectful. So when I got into the box, I just let them know we were not stealing signs and there was no need to be staring at us. He obviously didn’t take too kindly to that.”

Davis, who hit his AL-leading 39th homer Wednesday, said that Chapman “is a leader. He’s a natural at it. He might be a rookie but one day, he’s going to lead the way.”

In the second inning, Graterol snapped at Oakland outfielder Mark Canha; home-plate umpire Mike Everitt got between them and Everitt could be heard telling the Angels’ dugout that there were accusations of stealing signs.

“I don’t know if it’s their pre-pitch routine, but they have a habit of glancing back,” Angels manager Mike Scioscia said. “On a day game or a night game when you can see shadows and a catcher’s head, it’s easy to look back and pick up some locations. So, Juan was just saying, ‘Hey, man, don’t look back.’”

“We have video on what they do,” Angels starter Tyler Skaggs said. “If they need to look at signs to hit, it is what it is.”

Canha said that Graterol told him, “Stop looking at my signs,” and he had done the same thing to Chad Pinder. “Chad’s not the type of guy who would do that. I’ve never done that in my career,” Canha said. “I thought it was just a Scioscia-Angels-Graterol tactic to make young players get uncomfortable, just get in my head. I was just like, ‘OK, play your little games and I’m just going to focus on the task at hand.’”

Chapman wasn’t having it, but he said he used no swear words in the fourth when he spoke to Graterol. Graterol sprang to his feet and Everitt immediately separated them.

“I told him, ‘Don’t peek at the signs,’ because I saw him. Chapman told me, ‘We don’t peek at the signs,’” Graterol said. “I said, ‘Yes, you did.’ That’s it. We exchanged some words and that’s it. ... The umpire told him, ‘That’s enough.’ And he was still talking. That’s why he got thrown out.”

Everitt then gave Chapman a bit of a lecture, which is unusual. One scout said he found it “disrespectful. He’d never do that with an older player.”

“He said it had already been handled,” Chapman said of Everitt. “But obviously if I’d thought it had been handled, I wouldn’t have said anything. If it had been handled, (Graterol) wouldn’t have been continually staring at us when we were getting in the box. Obviously, I didn’t intend for it to go down like this, but the way I looked at it, I wanted to stand up for my teammates and for myself.

“Even though we are a young group of guys, I feel we deserve to be treated just like anyone else in the big leagues and be respected by our opponents.”

“It’s a nice thing to do, but I told him I’d rather have him in the game than sticking up for me,” Canha said.

The scout said that, in fact, he believed the Angels to be stealing signs during the top of the second inning.

Asked if the matter is over, Canha said he wasn’t sure. The teams do not play again until next spring.

Susan Slusser is a San Francisco Chronicle staff writer. Email: sslusser@sfchronicle.com Twitter: @susanslusser

On deck

Thursday

Off

Friday

vs. Astros

7:05 p.m. NBCSCA

McHugh (2-2) vs. Cotton (7-10)

Saturday

Doubleheader vs. Astros

1:05 p.m. NBCSCA

Game 1: Morton (11-6)

vs. Gossett (3-8)

Game 2: Peacock (10-2) vs. Mengden (0-1)

Leading off

Quite a month: Class A Stockton first baseman-outfielder Seth Brown was named the minor-league player of the month after hitting .349 with 12 homers, 38 RBIs, the most RBIs in August in pro ball.

— Susan Slusser