Walters, who was placed on the disabled list with right shoulder inflammation on June 14, felt some discomfort in his shoulder on Sunday but it's not considered serious.
He's expected to make another rehab start on Thursday after tossing five scoreless innings on Friday in his second rehab outing.
Walters is also scheduled to fly to the Twin Cities this week to meet with team trainer Tony Leo for precautionary reasons before heading back to Rochester.
"The plan is hopefully he'll be ready to pitch again Thursday down in Rochester," assistant general manager Rob Antony said. "He felt fine after throwing but today it felt like less than a bee sting. He just felt something. I don't think they're too concerned about it. He's coming to Minnesota over the break to see Tony and can see our doctors if need be. But we're not too concerned about it. But it would be good to get him one more before he gets rolling again."