As Oswalt was pitching, HP Umpire Jeff Nelson pointed to the pitcher midstream. Then after the pitch. Nelson seemed to call a balk, as he was moving his arms as if to say Oswalt did not come to a stop. However, instead of blowing the play dead and advancing the runner on 1B to 2B, he called ball 4 which also advances the runner but also gives the batter 1B. Very odd, never seen this before. At first I thought he called a balk, then I thought a quick pitch for ball 4, but at the end it was just ball 4 with a delayed balk calling.
During the broadcast the announcers said they spoke with observer Jim McKean, and he said this was the correct ruling.
Here is a link to the story that it explains it a lot better than I can:
http://mlb.mlb.com/NASApp/mlb/news/a...=.jsp&c_id=atl