Nelson backed off his throwing program over the weekend after experiencing discomfort, Adam McCalvy of MLB.com reports.
General manager David Stearns referred to the issue as arm fatigue, adding that he's "not particularly concerned at this point," per Robert Murray of The Athletic. Manager Craig Counsell also downplayed the situation, calling it a "very minor setback," so it sounds like the Brewers are handling Nelson with caution after he missed the entire 2018 campaign while working back from shoulder surgery. The 29-year-old is scheduled to resume throwing Tuesday, which bodes well for his availability for the start of the season. That said, Nelson's status will be worth monitoring as spring training progresses.