"It had been a while," Bass said.
Bass, the rookie right-hander, was summoned from the bullpen against the Mariners as starting pitcher Dustin Moseley failed to complete five innings.
Bass allowed one run on two hits over 2 1/3 innings with two strikeouts and one walk.
It was the first time Bass had pitched in his second stint with the Padres and it was his first pitching appearance of any kind since June 23 with Double-A San Antonio.
"I had the mindset that I was going to throw as many strikes as I could throw," Bass said of his first Major League relief appearance.
Bass made his Major League debut as a starting pitcher on June 13 at Coors Field, where he allowed one run on five hits in five innings, and won his debut in a spot start. He was then sent back to San Antonio after the game.
Bass felt OK about his outing against the Mariners, though he admitted that he felt like he was rushing himself.
"It was pretty good, but I was working faster than normal," Bass said. "I was excited to get in the game."