I am not sure if you can reproduce this. The only change i made to my game was setting the video memory to 2048 and changing the texture quality/filtering to very high.
edit: changed the settings back and it still was happening. I turned on mouse smoothing and it seemed to happen less. My friend also said it happened to him. I have a video of it but i will need to edit it as i didnt have audio enabled. I will upload it and link it here when i get time tomorrow.