Munson, who serves as left-hander Wandy Rodriguez's personal catcher, was 3-for-5 with two RBIs during the Astros' landslide 10-3 win.
That performance alone made Munson's batting average jump more than 40 points, from .242 to .289 -- which is what happens when a player has only 38 at-bats on the year.
"He's been swinging the bat, he's driven in a couple of runs," Garner said. "I feel comfortable with him at the plate. Early on, he didn't have any hits, but he's [had] some good at-bats, for a guy that's not getting to bat very often."
Although it's likely Munson feels a little extra pressure to perform during the rare times that he plays, he tries not to think about it when he's at the plate.
"You try to not put it on yourself," he said. "When you are a part-time player, whenever you get in there, you want to do something. You don't want to just be there and take an 0-fer or stink defensively. You want to do something while you're in there, to feel like you're helping the team."
Munson made the team out of Spring Training as a non-roster invitee after producing one of the highest batting averages of all position players. Garner is pleased with his contributions so far in the early stages of the season and is impressed with what Munson has been able to do in a short time span.
"It's particularly tough on him," Garner said. "He's not a veteran, although he's been around for a little while. He's not established at the big-league level. Playing once a week, it's difficult for him. I think he's handled it pretty well."
Sightseeing: Brad Lidge isn't one to sit around and waste time, and this week, he's taking DC by storm with his wife, Lindsay, and their daughter, Avery.
The Lidge clan has been out and about in the nation's capital, taking in as many landmarks as possible, including the Lincoln Memorial, the Smithsonian, the Natural History Museum and several war memorials.
"You can stay in your hotel room, or you can get out and see what each city has to offer, and that's what I want to do," Lidge said. "Some cities don't have a whole lot to offer. In Washington, there's so much to see, that if you don't take advantage of it, you're just wasting your time."
Hospital visit: Most of the Astros traveling party visited the Walter Reed Army Medical Center on Tuesday. The patients at Walter Reed are soldiers who were wounded in Iraq, many of whom lost multiple limbs as a result of combat.
As was the case during their visit last year, the Astros were impressed with how optimistic the patients are, even under the most trying circumstances.
"Just seeing their positive spirit is what's so impressive to me," Morgan Ensberg said. "Men and women -- soldiers -- who have gone through really horrible experiences, they come out so positive. They're working their tails off to get to healthy enough to get back to normal tasks.
"You become so inspired. They're not feeling sorry for themselves whatsoever. I'm thankful that they protect us, that we get a chance to live such a safe life. We don't think about these things. We don't think about the dangers of the world, because our military protects us."
New perspective: Garner watched Monday's game from a "confined space" -- most likely, the manager's office in the visitor's clubhouse -- and acted as many of us do when watching a team we care about. He yelled at the television ... often.
Garner, who served his one-game suspension during the Astros' win over the Nationals, was especially frustrated during the fifth inning, when Rodriguez walked three batters.
"What's bad about watching on TV is he threw two strikes to [Royce] Clayton that he didn't get called," Garner said. "I was screaming at the TV then. But on balance, I thought the umpire did a pretty good job."
Coming up: The Astros and Nationals continue their extended series on Wednesday, meeting for game three of the four-game set at 6:05 p.m. CT. Right-hander Roy Oswalt (5-3, 3.57 ERA) will face left-hander Mike O'Connor (2-2, 2.89 ERA).
Alyson Footer is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.