This circling business is simply the dog saying: “Look dad, look how clever I am” and it needs to be nipped in the bud before it becomes habit forming.
First step is to stop sending the dog for retrieves in the open because this makes control very difficult.
Instead, find a place where you can stand with your back against a hedge, fence or wall so that the dog can’t get behind you.
Even better if you can find a narrow path or lane that’s enclosed both sides because it means the dog has got to return straight to you, and can’t deviate.
All you need to do is drop a retrieve, walk on a little way with the dog, then send it back.
Next, stop the dog on his way back when he gets almost to you then step forward without letting the dog get passed you.
Gently take the retrieve from him and repeat the exercise one or two times a day until he has got the message to come straight in and deliver the retrieve.