My immediate reaction was 'light leak' too. Curious it is in approx the same position on every frame, but maybe this is where the exposed frame sits after you wind on? If so - you could reload a film after exposure (or even just use a few frames). Place one frame accurately in the film gate and the next frame should show you exactly where the light leak is. Because it just looks like a little flare, it must be a very slight leak, might be tricky to find. Try placing some black PVC tape over the area (I bet it is the hinge) and shoot another film, to convince yourself it is a light leak.