Webb said he isn't concerned at the moment.
"No, no, I think it will be fine," he said.
Webb, 22-7 with a 3.30 ERA last season, was the runner-up to Giants right-hander Tim Lincecum in the voting for the National League Cy Young Award, an honor Webb captured in 2006.
But even last year, Webb said he battled through an early bout with right shoulder tendinitis and needed four starts from Aug. 26 to Sept. 12 to notch his 20th victory.
In the three starts leading up to No. 20, Webb allowed 22 hits and 21 runs (19 earned) in 13 2/3 innings for a 12.57 ERA. He didn't get through the fifth inning in any of those starts.
He came back, though, to win three of his final four outings.
But this spring, Webb had a start pushed back because of tightness in his right forearm.
"You know us pitchers," Webb said. "We're always working through all kinds of stuff."
Webb, 29 and a veteran now of five big league seasons, noted that the shoulder stiffness on Monday contributed to a marked decrease in his velocity, because he was trying to find the right slot to rotate his arm as he followed through on his delivery. Webb is most effective when he's able to come right over the top, allowing his trademark sinker to drop. His sinker flattens out as his arm motion dips even slightly to the side.
It all sounds eerily familiar to the problems he noted during his slump last year.
"I mean, it's similar," Webb said. "Pitchers go through times when you try to find the right spot and you try different things. You just have to kind of work through it until one day you find it, it clicks and you're able to repeat it."
Webb had a fairly easy first two innings, hitting the game's first batter and allowing a single to lead off the second, but facing the minimum six batters. Then the stiffness began to set in.
"I saw a guy who's making his first start of the year and is knocking some of the rust off," said D-backs catcher Chris Snyder, talking about a pitcher whose velocity decreased into the mid-80s late in his stint.
Take note that last season there was no rust to knock off. Webb opened 10-0 in his first 10 decisions, including six innings of two-run, three-hit ball in a victory over the Reds on Opening Day.