i hope you can do this often !
once you get a collection,
you can call the travel channel and get
your own tv show :)
Everyone here has some awesome explanations! I'm pretty sure it's not a light leak, though...as I did get that fixed. Breath condensation is a good one. Shocking the emulsion is a good one. Even the developer could be something...not too sure about the mold/fungus, though. Maybe the boy funk fumes in the bathroom that serves as my darkroom? :)
To be honest, I like the 'ghost' idea best. I'd LOVE to get more 'ghost' pictures! I'm going to load her up again tonight and leave her in my attic (totally empty) for the night and see what I get in the morning.
You said "tin." Is your pinhole camera made of metal? If so, condensation could have collected between the paper and the camera either freezing or soaking into the paper.