But the left-hander and the Astros are still encouraged.
Rodriguez allowed six hits in 2 1-3 innings, but he didn't take the loss.
Rodriguez posted career bests in ERA (4.58) and starts (31) in 2007.
The Astros are hoping to move him into the number two spot in the rotation behind ace Roy Oswalt.
Rodriguez said his curveball and his location were better than his first spring start against Cleveland last week, when he struck out three in two scoreless innings.