Manager Matt Quatraro said Friday that Harvey has been dealing with back tightness, Anne Rogers of MLB.com reports.
Harvey picked up his first save of the season Sunday against the Tigers, but his back issues have prevented him from pitching since then. The Royals skipper didn't give any indication that the 29-year-old reliever will need to spend time on the injured list, but there is also no telling when he'll be available out of the bullpen again.