Cahill has been on the disabled list since July 1 with a right hip contusion, but he experienced some discomfort in his shoulder earlier last week after playing catch.
The shoulder soreness has gone away Cahill said, and it sounds like his hip is coming around.
"It never hurt right away," Cahill said of the hip. "It was just like when I sat down and got up it would just cramp up kind of."
D-backs general manager Kevin Towers said Thursday that it looked like Cahill might not be able to return until early August.
"I have no idea," Cahill said on when he might return. "I'm just building back up and working on some things and hopefully the health is there so I can finish better than I started."
Steve Gilbert is a reporter for MLB.com. Read his blog, Inside the D-backs, and follow him on Twitter @SteveGilbertMLB. This story was not subject to the approval of Major League Baseball or its clubs.