Don't worry it's perfectly normal and quite funny once you realize what's happening.
They have a pecking order which gets challenged sometimes. As you said it was a "get lost" peck, nothing too nasty.
One of my girls (Amber) doesn't realize that she's at the bottom of the pecking order and is faster than the others when it comes to stealing food. I was watching one morning when the top hen (Poppy) was pecking at a large treat after Amber had taken a piece and ran off with it to eat. Before Poppy managed to eat much, Amber was back and circling. She managed to nick the whole piece off Poppy and legged it round the corner before Poppy realized what had happened. It was so funny, especially the bemused look on poor Poppy's face.
Cheers.