He had taken a no-hitter into the eighth inning during a game one week earlier.
"You shoot for perfection and if you don't get it, you're still up there," Gamboa told MiLB.com. "Every pitcher that goes up there tries for that. You step on the mound and you go for a perfect game.
"No matter what level you're at, a no-hitter is a difficult thing to do. I'm very excited and grateful to have this moment with the Bowie Baysox for everybody on the field."
Gamboa, who has been in the Minors for six seasons, struck out five batters and walked three. He threw 103 pitches, 58 for strikes.
With Bowie this season, he's thrown 93 innings and fanned 76 while posting a 3.48 ERA.
Gamboa said he threw his knucklball about 75 percent of the time on Sunday.
"I used to really grip it deep in my hand, now I'm loose on it, just on my fingertips," said Gamboa. "It has been good and consistent and it has been moving. My biggest worry is always that it won't move at all. I don't want to go up there and just throw BP."
Jason Mastrodonato is a reporter for MLB.com. Follow him on Twitter @jmastrodonato. This story was not subject to the approval of Major League Baseball or its clubs.