KISSIMMEE, Fla. — Astros reserve outfielder Fernando Martinez (back) was a late scratch from a spring training game Thursday against Detroit. Martinez, 24, missed several games earlier this month and said Thursday his back continues to be sore. There isn’t much pain, but Martinez feels tightness in his lower left side. “We’ll see what happens in the next couple days,” said Martinez, who doesn’t believe he’s headed for the disabled list but will be re-evaluated in Houston. “It’s just a little pain.” Martinez hit .344 with one home run and six RBIs during the spring. Asked about missing more time, he said, “We’ll see. We’ll see.” Twitter: ChronAstros