Strangest thing... I went to the ATT store and it stopped doing it for a few hours, then it came back. Couldn't recreate the issue with a stock S3 in the store either. No fix yet :(
Scott,
Is your phone ATT? The Samsung tech I spoke with wasn't able to recreate the issue with his T-Mobile S3. Next step for me is to go to the ATT store and see if we can recreate the issue from one of their 'known-good' S3s.
I'm on the phone with Samsung support right now... will see what happens if I ever get off hold. This was not an issue with the Galaxy S2... it's new with the S3 (or Jelly Bean, or something).