I looked at the images posted on the "color film" forum, and I agree with shutterfinger, it looks like you have a bellows light leak.
The film sits slightly behind the film gate, so a leak in the bellows imprints an image offset from the lens due to parallax. The longer you have the bellows extended, the more the fog - maybe you can remember and correlate that with the images you took. Also the fog is consistent to one side of the frame, that and the parallax offset should direct you to the side of the bellows that the leak is coming from (usually the opposite).