From the OK Gov:

I, Mary Fallin, Governor of the State of Oklahoma, pursuant to Section 10 of Article 6 of the Oklahoma Constitution, hereby grant a stay of the execution of Richard Eugene Glossip of thirty-seven days from the current scheduled date of execution, September 30, 2015. This stay is ordered due to the Department of Corrections having received potassium acetate as drug number three for the three-drug protocol. This stay will give the Department of Corrections and its attorneys the opportunity to determine whether potassium acetate is compliant with the execution protocol and/or to obtain potassium chloride. The execution for Richard Eugene Glossip is therefore scheduled for Friday, November 6, 2015.

Technically that is a reprieve, not a stay.  The referenced section of the state constitution says, "The Governor shall have power to grant after conviction, reprieves or leaves of absence not to exceed sixty (60) days, without the action of the Pardon and Parole Board."

Glossip's petition to the U.S. Supreme Court was denied today with only Justice Breyer noting a dissenting vote.  They evidently were not impressed with his actual innocence claim, in contrast to Troy Davis, where they sent the case to a federal district judge for a full evidentiary hearing (at the conclusion of which he declared Davis's innocence claim to be "smoke and mirrors.")

Odd that potassium chloride would present a problem.  That is nothing fancy, just a simple salt.  Non-sodium table salt substitute (yuck) is often potassium chloride.