Alison Krauss has rescheduled five shows, and cancelled two others planned with Willie Nelson so she can undergo a minor medical procedure. The start of her tour is being pushed back one week.

“She just has to rest up a few days,” Rounder Records spokeswoman Regina Joskow told the Augusta Chronicle last week. Krauss will return to the stage on May 8.

No further details were revealed, however the famous bluegrass singer’s website indicates the matter was serious. “Due to an unforeseen and urgent health concern that requires immediate attention, we have been forced to reschedule and unfortunately cancel a few select shows on the upcoming tour with Willie Nelson,” the statement reads. “We sincerely apologize for any inconvenience.”

Last fall Krauss was forced to go on hiatus to treat a vocal condition called dysphonia. At that time the singer was expected to make a full recovery. It’s not clear if the two incidents are related.

Shows planned between May 1 and May 6 were rescheduled, while shows planned for May 17 and May 18 were cancelled. New dates, and refund policies are available at Krauss's website. The tour will now begin on May 8 in Daniel Island, S.C.