[Kali_Namir]

It sounds to me like you've simply got a teacher who believes you can do better and is singling you out in an attempt to make you do so. In these cases most teachers will make you embarrassed so that you will strive to do better and better, yes it sucks, and yes you may be unable to help it, but the only thing you can do at this moment is either talk to him in person and explain what is happening or ask him why he is doing it, or simply ignore it and go on with your day to day activities.