Mine would sometimes idle at almost zero. Who knows what would cause it, but you could clearly hear each cylinder fire. Pop, pop, 1 , 3, 4, 2.
I would let it idle like this for a while cause it was weird and sounded cool. Didn't notice that the oil pressure was at almost zero, too.
Letting it run like this may have been the cause of 3 cam lobes getting rubbed off. I'm not sure if it was a coincidence or not but I do know that I don't let it ever idle this low anymore.

Normally, my A12 idles at around 1500rpm.