Because the problem appeared on only one of two rolls, and only on the first three frames, it’s less likely to be a persistent camera fault. That pattern points more toward a film-specific issue, such as handling during loading or a minor problem with that film cartridge.

If the camera had a consistent body light leak, you’d usually expect it to show up more regularly across multiple frames or multiple rolls. Since later frames on the same roll were fine, the issue was likely limited to the start of that roll.

The practical next step is to shoot a couple more rolls and see whether it happens again. If it does not recur, the most likely cause was something specific to that roll or how it was loaded rather than the Leica itself.