Fleecehusband was in the workshop and his hands were all oily, so definitely not him
The lids are gingham check so I could watch the pattern turn itself

I hadn't looked away. It was probably poltergeists as Bionic Sally says

I grew up in a haunted house but I didn't think this one was
Maybe I put them on when the jam was still too hot, but I always let it stand for 5 mins before I put it in the jars, to cool a little so the fruit doesn't rise to the top, so it wasn't extra hot.
I wondered if there was a film of moisture around the rim of the two freaky jars - maybe I hadn't dried them properly and that was enough to lubricate them when Doganjo's increased pressure had its effect. Or,

the lids were cold and the jam was hot, so the lids tried to expand in the heat, which made them turn. It didn't do it after a few minutes.
Next batch of jam I'll experiment and see if I can make it happen again.